It wouldn’t be pistols. If you’re talking about actual military operations, handguns occupy a position somewhere between “badge of office” and, “that’s cute, it thinks it’s a gun.”
Before I get going, I’m going to be naming a lot of guns, feel free to Google Image Search these as you’re going, so you can get an idea of what I’m talking about. When it comes to the firearms themselves, my recommendations are about near future aesthetics.
If your characters are dealing with an area where there are a lot of civilians they don’t want to kill accidentally, you’re probably looking at SMGs and shotguns with an ammunition solution.
Rounds like the Glaser safety slugs are expensive as hell, but frangible ammo might be a good solution when dealing with combat where you do not want blowthroughs. Also, if you’re talking about DoD contracts, you could expect the price on those rounds to be a little more manageable.
Even if that’s the case, in fairly tight quarters combat shotguns are still a solution to both the blowthrough issue, and a good close combat weapon choice.
The Kel-Tec KSG might be a good one to look at. The UTAS UTS-15 might not be a bad shotgun to look at.
Now, actual urban combat presents a real problem for weapons. Full size rifles are very awkward for room clearing and moving through tight spaces, but SMGs don’t (usually) have the accuracy to replace a combat rifle in engagements at ranges over 100m.
One of the biggest solution has been bullpup weapons. These are weapons where the grip is located towards the front of the gun. The FN P90 is an excellent example of the design that’s all over the place in popular media.
In close quarters, a shorter weapon offers enemies less to grab in the event they try to get the gun away from the shooter. It also provides less to get caught on the environment, and, in general, allows more mobility. This is part of why SMGs and compact rifles are preferable in city fighting situations.
Normally, when you simply shorten the barrel, you end up with a firearm that’s harder to control and less accurate. Bullpup designs get around this by keeping the barrel length, and by using the stock as an integral part of the firearm instead of dead weight.
This results in compact, highly accurate, assault rifles that can be used indoors and in the streets.
You might want to look at the FAMAS, FN f2000, Enfield L85 and FN P90 for inspiration here. Also, if you want a more rugged looking bullpup, the Russian OTs-14 “Groza” (“Thunderstorm”) might be a good choice. As I recall, the OICW was also supposed to be a bullpup when finished, that project was abandoned about a decade ago.
The FAMAS is a bit bulky, but it already looks like it belongs in a sci-fi movie. The L85a2 is (reportedly) incredibly accurate in the right hands. The P90 is technically an SMG, (because the FN Five-Seven uses the same round) though, honestly it’s a weird little monster all it’s own; not a true assault rifle, but with some of the characteristics of one.
Beyond this, there are also a few very compact SMGs like the H&K MP7 and MP9. The KRISS Vector probably deserves a mention, this is a new .45 that has a fairly compact form, and an interesting recoil control mechanism, that redirects the force down, reducing climb. This technically isn’t a bullpup, but it’s worth looking at. Just keep in mind, all of these would be substandard solutions because your characters would have to switch weapons when heading outside.
It’s worth pointing out, that for law enforcement, SMGs are actually a better choice. Combat rarely occurs at long range, outside of dedicated police marksmen/snipers), so the short range of an SMG actually becomes an advantage.
If you’re wanting some high tech pistols to go along with them, the Berretta PX4 (this was Cobb’s pistol in Inception), the H&K USP and USP compact (the USPs actually have an internal counter-spring that does amazing things to reduce recoil), the Walther P99 (this has also been used in a few of the more recent Bond films, and I distinctly remember a sci-fi film trying to pass them off as distant future hardware), the SIG Sauer SigPro pistols (like the SP2022).
I know I’m missing some examples there, but that should give you a start on what you want to tinker with.
If you’re a gamer, Call of Duty: Black Ops 2 is a virtual buffet of near future hardware to play with, including a lot of non-weapons tech, interspersed with levels set in the 1980s. Crysis 2 has a nice mix of modern/near future weapons in an urban environment, though the focus there is the nanosuit… and alien invasion, rather than high tech guns. (I’ve also got a soft spot for Crysis’ take on the FN SCAR.) Come to think of it, Deus Ex: Human Revolution might be a bad choice, again the guns aren’t really the focus, but it might mesh with what you’re trying to do.
If you’re not a gamer, or at least not that kind of gamer, some of the old Shadowrun source books might be worth looking at as a reference. Just be prepared to filter out the fantasy elements you don’t want from the ones you do.