My five, in no order:
1. CZ 75. Fantastic ergonomics, very soft shooting, easy to be accurate with (despite a very pedestrian trigger). Just about everyone who shoots these can shoot accurately, right away. With a little trigger work, they become perfect duty weapons. Many of the clones are every bit as good.
2. Sig Sauer P226 Navy. My experiences with the P226 have been flawless, and this model brings a rail and a ridiculous finish to the party. Another 'OK' trigger, but everything else is great.
3. Beretta M9. Brilliant design. Reliable, resilient, and easy to shoot accurately. Sexy. Rugged enough for heavy use and abuse, and still cool enough to have been carried by John McClain and Murtaugh.
4. HK P7. Unique. Stupid accurate. Tough.
5. Caracal C. I'm being serious. I believe that (following the firing pin block fix), this is the best polymer pistol on the market. Glock reliability-through-simplicity, an out-of-the-box trigger almost equal to the PPQ's, versatile size (great for duty AND concealed carry), bore axis similar to the Ruger SR9. It's basically perfect. It has already passed both the German Police tests, and NATO tests.
Through working in the gun business, I've met a ton of wannabe operators, a lot of former servicemen who embellish what they did, and... a few guys who have been really deep in it. Here are some opinions from some serious guys, from in-house "best/favorite" conversation:
1. Actual former (Army) operator: M9. When asked why this was his choice, he said, "Because we (team) actually had to USE our sidearms." That was all the answer he gave.
2. Former Ranger/current contractor: "Handgun? Who cares? Give me an HK416."
3. Former private security contractor: "HK P7" (note: despite raving about the P7, he actually carried an HK USP 9 compact. The P7's weakness is capacity.)
Intentionally left off my list:
1. Browning Hi-Power. Certainly one of the most relevant designs in history, but the trigger is not great, and it has teeth. While I consider it one of the best collector pieces out there, it is no longer a superior sidearm.
2. Glock. 15 years ago, this would have made the list. I can't put it on today, given that the XD, XDm, M&P, P99, PPQ, SR9, HK P2000, HK P30, HK USP, FNH FNS 9, and other firearms are roughly equal to Glock, or arguably superior. While many people will disagree with some particulars I've mentioned in this breath, the bottom line is that Glock does not stand above its peers, anymore. It's just 'one of the guys'.
These are opinions, of course. You may disagree.