2017 is drawing to a close, and it's been quite a ride. The S&P 500 market index has gained 18% year to date while the Nasdaq Composite index has jumped a stunning 26%. December is a popular time to rebalance your investment portfolio for the new year, taking profits or recording losses for the expiring tax year.

Those freed-up assets need to go somewhere, of course. So, what are the best stocks to buy right now? That's what we asked a handful of investors here at The Motley Fool, and they were quick to come up with some excellent ideas.

Read on to see why our panelists recommend buying Costco Wholesale (COST 1.53%), Camping World Holdings (CWH -0.08%), CVS Health (CVS -0.12%), T-Mobile US (TMUS -0.35%), and Bitauto (BITA) right now.

Stock tickers with rising arrows

Image source: Getty Images.

A Chinese growth stock at a bargain price

Brian Stoffel (Bitauto): Last week, I purchased shares of Bitauto for my own portfolio, and if you have the stomach for volatility, a diversified portfolio, and a long-term horizon, I think you should consider doing the same this December.

Bitauto maintains a platform that aims to make the car-buying experience more streamlined for Chinese citizens. The company's legacy business is in advertising and running marketing campaigns for auto dealers.

But what's really got me excited is Bitauto's transaction platform, Yixin, which began operating in 2015. The platform -- which connects buyers with dealers, financiers, and insurance companies -- has shown remarkable growth. Revenue from the division is up 374% since 2015 to $470 million. It now accounts for 41% of revenue and is beginning to show signs of a powerful network effect.

A special situation makes buying right now particularly appealing. Yixin was spun out of Bitauto on the Hong Kong exchange last month. Bitauto has retained a controlling 44.4% stake, while three of China's strongest Internet companies -- JD, Baidu, and Tencent -- control another 35.8%.

And yet, as of this writing, Yixin trades with a market cap of $5.64 billion. That means Bitauto's cut is worth $2.5 billion. But Bitauto's stock, which trades on the New York Stock Exchange, is currently valued at just $2.1 billion. If you buy shares now, you not only get Yixin for a 16% discount, but you get all the rest of Bitauto's non-Yixin businesses for free!

The next chapter could be even better than the last

Cory Renauer (CVS Health): The last big chapter of this stock's growth story began in 2007 with the addition of the pharmacy benefits management business that has since become the country's largest. The stock tanked after the announcement, but has delivered a market-beating 184% total return since the company stated its intent to merge with Caremark 11 years ago.

The next several months will be nervous ones as antitrust regulators weigh the pros and cons of CVS Health's proposed merger with Aetna, a major U.S. health insurance provider. Despite operating as an end payer in the embarrassingly wasteful U.S. healthcare system, Aetna's operations sailed through the financial crisis and the Obamacare rollout without slipping into negative territory once. Although it could take a few years to work out the kinks, I think this bold move will go a long way to lower expenses and widen Aetna's profit margins even further.

Another insurer, Anthem, and the country's largest independent pharmacy benefits manager, Express Scripts, recently showed us just how beneficial it's becoming to bring this service in-house. Express Scripts took over Anthem's pharmacy services in 2009 when it bought Anthem's in-house pharmacy benefits manager for about $4.7 billion.

Anthem's shareholders got a raw deal when management agreed to a higher sale price in return for less-than-competitive pricing from Express Scripts over the life of a 10-year contract. Their expense is our lesson as the insurer now complains that Express Scripts is negotiating discounts and rebates for Anthem in excess of $3 billion each year that it isn't passing along.

While we can't really be certain CVS Health's PBM segment will negotiate prescription drug savings of a similar amount for Aetna, the combined company isn't going to take itself to court after keeping every penny wrangled from the world's drugmakers.

Pitch a tent with this stock

Dan Caplinger (Camping World Holdings): Few investors would expect to find fast growth in the recreational vehicle industry, which for the older among us brings back memories from the 1960s and 1970s of avocado green and harvest gold upholstery and countertops in campers and conversion vans. But the RV industry has made a comeback, and Camping World Holdings is trying to position itself as the retail leader in all things related to recreational vehicles.

Recently, millennials have realized the value proposition of bringing your own lodging with you on road trips. Cheap gasoline has also helped make RVs a more affordable mode of travel. Yet Camping World seeks to go a step further than just cashing in on favorable sales trends, instead establishing a community of like-minded enthusiasts who can interact with and support each other. That's been a winning business model for Camping World, and CEO Marcus Lemonis sees more success ahead as the company moves beyond RVs to broaden its reach into the larger outdoor lifestyle consumer market.

Camping World isn't a pick for the meek, as it has already picked up more than 50% in just the past six months. Yet RV dealers see strong demand continuing into 2018. If the retailer can capture greater network effects and foster loyalty in its customer base, then Camping World could see even bigger gains in December and beyond.

A young woman points at a store window with a big smile.

Image source: Getty Images.

Stuff your holiday stocking with this retailer's shares

Todd Campbell (Costco Wholesale): Costco Wholesale is about as close as you can get to a competitor that can compete toe-to-toe with Amazon.com, and that makes it a stock worth stashing away in December, especially given this year's holiday shopping trends.

According to a National Retail Federation and Prosper Insights & Analytics survey, more than 174 million Americans shopped in-store and online from Thanksgiving through Cyber Monday -- 10 million more people than they anticipated. Over the five-day period, shoppers spent an average of $335.47 per person, putting them well on their way to the $967.13 per person in spending that's expected this year.

A lot of this spending is happening online, but Costco's rock-bottom prices should still allow its warehouses to capture their fair share of sales. Costco won't be left totally out in the cold in terms of e-commerce, either. The company's made e-commerce more of a priority this year, and while it represents only a small piece of its revenue, online sales increased by more than 40% year over year in the 12 weeks ending Nov. 26.

Overall, Costco's net sales increased 13.3% year over year to $31.1 billion over the 12 weeks ending Nov. 26. Excluding volatile gasoline sales and currency exchange impacts, net sales still grew by a healthy 7.9% year over year.

Given those growth figures, it wouldn't surprise me if Costco's sales were to grow more quickly this holiday season than the 3.5% to 4% that Visa expects. If I'm right, then giving yourself the gift of Costco's shares in December could be smart.

Two uncomfortable value boosters

Anders Bylund (T-Mobile US): This wireless network giant is always on my watch list for interesting investment options, but recent events have moved T-Mobile to the very top of that heap.

A chronically undervalued disruptor and innovator, T-Mobile's shares are currently available extra-cheap due to the loss of a few merger options. The long-running saga of jilted partners that has been playing out between Sprint and the magenta network over the years was recently put on the back burner again. Taking that game-changing merger off the table put a damper on the stock, which now has underperformed the S&P 500 index in 2017 after crushing it over the last few years.

T-Mobile keeps setting the standards for other telecoms to follow, generating $10.2 billion of trailing EBITDA profits even while offering low service prices and lots of expensive incentives to new subscribers. The latest Un-carrier policy saw the company paying their customers' Netflix fees in full. That's a crowd-pleasing move.

In short, this is an innovator that isn't afraid of slimming down its profit margins in order to steal customers from the two bigger U.S. telecoms. And that ties right into the other potential trigger for even greater gains.

While my fingers are crossed for some miracle stopping the FCC's attack on net neutrality rules, and with the understanding that T-Mobile doesn't exactly play in the household broadband space, I could see T-Mobile using that as a springboard into new business. If the duopoly at the top start exploiting the new rules to boost their own profits while adding costs and cutting down on consumer-friendly plan features, that would be a green flag for T-Mobile to go in the opposite direction. That could attract millions of low-hanging subscribers in a hurry.

So T-Mobile shares look affordable right now, and the company could be a big winner if the FCC goes through with its current plan to cancel net neutrality protections. This could be the perfect time to build a T-Mobile position.