When you're looking for a doctor or a lawyer, you focus not just on professional qualifications and expertise. You want those things, but you also want someone who will fit well with your personality.

The same holds true with picking a broker. Sure, you want a broker who'll let you buy and sell stocks efficiently and inexpensively, along with the resources to help you make informed investment decisions. But beyond that, you know that you'll be counting on your broker at some critical times. You want to be sure that you have a good fit with whichever broker you pick -- because you'll be surprised just how much your investing results may improve with the right match.

Looking at the lists
Researching brokers, you'll find a number of surveys and other rankings of dozens of brokerage firms. For instance, a recent issue of Barron's rated 25 top online brokers on a wide range of factors. The complete list included some brokers that I had never heard of, but the results were similar to those I had seen in other similar lists:

  • For those who trade infrequently and tend to hold for the long term, well-known names like Fidelity, optionsXpress (NASDAQ:OXPS), Charles Schwab (NASDAQ:SCHW), and E*Trade (NASDAQ:ETFC) were among the top six picks.
  • For more sophisticated traders who trade frequently, use options, or invest on international exchanges, companies like thinkorswim (NASDAQ:SWIM), Interactive Brokers (NASDAQ:IBKR), and TradeStation (NASDAQ:TRAD) found their way toward the top spots.

On a superficial level, these rankings seem logical. Occasional traders and buy-and-hold investors don't have to worry as much about finding the absolute lowest commissions they can, because they don't get penalized as much for paying a few extra dollars per trade. When you make hundreds of trades per month or need specialized services, however, costs become a much bigger issue, and there won't be as many providers who can meet your needs.

But don't take those lists too seriously. Different surveys have put other brokers, including ShareBuilder, Scottrade, and TD AMERITRADE, closer to the top. A lot depends on the methodology a particular study uses, and results can vary widely just by tweaking a few basic assumptions.

Beyond the numbers
More importantly, raw survey results and summaries simply can't take the place of personal experience. If you get the wrong feeling from working with a broker, then it'll affect your results. If that happens, you should switch -- even if you end up choosing one that's further down whatever list you're looking at.

For instance, I've had a lot of experience with one top-rated broker on the Barron's list. During last fall's market panic, I tried to take advantage of the short-term chaos by picking up beaten-down shares of companies that I thought provided good long-term value, including Freeport McMoRan (NYSE:FCX).

Yet on several of those occasions, that broker's online system crashed -- or even worse, accepted my stock order but then took as long as 30 minutes to acknowledge that it existed, leaving me completely paralyzed as I waited to see if the order had filled correctly.

Now most of the time, this broker has provided good service. But because it failed me when I needed it the most, I now rely on another broker for time-critical trades -- even though my original broker meets more of my overall needs.

Know what matters
Timely executions and online functionality happen to be my hot-button issues, but you may have a completely different one. Perhaps you want 24-hour customer service to help you whenever you have a problem. Maybe you want a broker with great tools that let you analyze options strategies or trade futures.

Whatever you're looking for, see if you can take a test run before you move your money. Although survey rankings may give you a starting point, nothing beats the experience of actually looking at and experiencing brokers on your own. And feeling comfortable will help you invest better.

One thing is true for everyone, though: If you're dissatisfied with your broker, there are few good reasons not to switch. Competition is fierce, and you're bound to find someone who gives you exactly the right mix of services at a price you're comfortable with. So don't waste another minute: Find yourself a better broker today!

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Fool contributor Dan Caplinger is happy with his broker setup. He still owns those shares of Freeport McMoRan. optionsXpress Holdings and Charles Schwab are Motley Fool Stock Advisor recommendations. Try any of our Foolish newsletters today, free for 30 days. The Fool's disclosure policy is a perfect fit.