You might think high-yield dividend stocks would be boring. Think again. Quite a few stocks with mouthwatering dividends were downright exciting in 2019, delivering sizzling gains.

Three high-yield dividend stocks that ranked among the best performers last year were Innovative Industrial Properties (NYSE:IIPR), Seagate Technology (NASDAQ:STX), and Taiwan Semiconductor Manufacturing Company (NYSE:TSM). Each of these stocks soared 50% or more in 2019. Here's how they achieved such impressive returns and whether or not they're smart picks to buy in 2020.

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1. Innovative Industrial Properties

Pot was hot for at least one company last year. Shares of cannabis-focused real estate investment trust (REIT) Innovative Industrial Properties skyrocketed by 67% in 2019, ranking as the second-best U.S. marijuana stock of the year.

IIP continued its "rinse-and-repeat" approach, reinvesting cash to buy additional medical cannabis properties. The company entered 2019 owning 11 properties in nine states. By the time the famous ball dropped in Times Square on New Year's Eve, it claimed over four times as many properties spread across 14 states. This significant expansion fueled a huge rise in revenue for the company.

In many cases, the kind of gains racked up by IIP would cause a company's dividend yield to fall. However, the cannabis REIT's dividend yield went up as its share price soared thanks to a string of big dividend hikes. IIP's dividend currently yields nearly 5.5%.

2. Seagate Technology

Seagate Technology is accustomed to cyclical peaks and valleys in the hard disk drive (HDD) industry. Last year was interesting in that the company faced headwinds throughout much of the year while its stock zoomed 54% higher.

Because of the challenging market dynamics, Seagate's revenue fell in 2019 compared to the prior year. However, the company's earnings improved. And Seagate consistently topped Wall Street earnings estimates quarter after quarter. In the latter part of 2019, the company began to see higher demand and even posted exabyte shipments that were near record levels in the quarter ended Oct. 4, 2019. 

Seagate boosted its dividend payout in 2019 for the first time in several years. However, that increase wasn't enough to keep its dividend yield from declining as its share price climbed. Seagate began 2019 with a dividend yield close to 6.5%. Its yield now stands at nearly 4.4%.

3. Taiwan Semiconductor

Taiwan Semiconductor started off 2019 predicting weak sales growth. Sure enough, the big chipmaker reported a year-over-year revenue decline in its first-quarter update. But Taiwan Semiconductor's fortunes improved throughout the year, leading to its stock vaulting 57% higher in 2019.

The primary driver behind Taiwan Semiconductor's strong performance last year was the increased adoption of its 7-nanometer technology. New smartphones, including those supporting 5G high-speed networks, and new high-performance computing applications using its chips boosted the company's revenue.

In addition to Taiwan Semiconductor's impressive stock performance, investors were rewarded by the company's dividends throughout 2019. Its dividend currently yields nearly 4.2% -- and more dividend hikes could be on the way in 2020.

Are they buys now?

I think that two of these three high-yield dividend stocks are good overall picks for investors. Let me start, though, by addressing the exception. I'm not convinced that Seagate will be able to deliver the kind of growth that I'd prefer because the rising adoption of solid-state drives will probably affect HDD sales.

Will Seagate continue to pay great dividends? Probably so. As such, income investors might want to consider the stock. However, there are other stocks that I think have better risk-reward propositions and that also have attractive dividend yields, including Innovative Industrial Properties and Taiwan Semiconductor.

To be sure, both IIP and Taiwan Semiconductor face risks. The cannabis and chipmaking businesses are highly volatile. But I think that IIP will be able to keep up its winning ways by adding more medical cannabis properties. I also expect that Apple's launch of 5G iPhones in 2020 will pave the way for strong sales for Taiwan Semiconductor. My view is that Innovative Industrial Properties and Taiwan Semiconductor will deliver solid growth and great dividends to investors.