My preferences...
For revolvers, I prefer Ruger DA revolvers. I think that Ruger DA revolvers are the best revolver design on the market. Ruger's aren't that great cosmetically speaking and they have heavy triggers. Neither of these "problems" bother me because they are easy to fix. Rugers are, by far, the most durable DA revolver design on the market (solid frame and triple locking cylinders). I like Smiths and Colts, but I would never buy guns from either of those manufacturers. Rugers suit me too well to switch brands.
Autoloaders are a different story. I don't trust Rugers. I also don't trust 1911s, either.
In my opinion, there is no one company that makes the best autoloaders. Here are some lists of the guns and companies that I like and have experience with:
Metal frame autoloaders:
1. Sig arms (p226). I like them alot. Best overall quality in their class IMO.
1a. Beretta (92fs and 90two). I actually like the 92 series better than Sigs, but I think Sig uses better materials in their guns. If I ever buy a metal framed autoloader, it would probably be the Beretta 90two.
2. CZ. Very nice pistols. Great value.
3. Browning (I only would get one if I could find one of the discontinued HP chrome models)
Polymer frame autoloaders:
1. HK (USP and p2000). I think that the overall quality is better than Glock, but they are too expensive for my taste. I don't think that they are $200 better than a Glock.
1a. Glock (17 and 19) (Some of the best overall guns on the market)
2. Springfield XD
3. Smith and Wesson M&P.
In some ways, I like the XD and the MP better than Glocks, but they are both still relatively new. After a few more years, I might be willing to move one or both of these manufacturers ahead of Glock.
There are a lot of great options out there. I still don't own any autoloaders, but I plan on getting one this year (unless I find a 4" SS Ruger RedHawk at the local shop). I rent autoloaders at my local range every so often and have gotten a good feel for what I like in an autoloader. I only plan on getting one autoloader, and I'd like to wait a little longer to see how the Sig p250 works out. The gun is a little small for my taste, but I might consider getting one if Sig puts out a full-sized model in the next year or so. I don't want to have a huge handgun collection, I just want what I think I could one day need: .22, .357, .44 magnum, and one 9mm.