I have a Beretta and a 229. Both are excellent guns. Both are accurate and well made. The Beretta is insanely reliable (it'll fire ammo that jammed other guns), is easy and cheap to get hi-caps for, has an exposed hammer, safety/decocker, and is a classic. It's biggest drawback is the size: while it's not particularly wide, it's big and heavy.
The 229 is also reliable (though I'd give first honors to the Beretta), you can get 13 round hi-caps (though they're more expensive than the Beretta's), has an excellent trigger (better than the Beretta's), and while it doesn't have a safety, it does have a decocker. Regarding size, the 229 may be slightly wider than the Beretta, is just as heavy, but is smaller. Most would say the direct Sig competitor to the Beretta is the Model 226, not the 229.
I don't have much first hand knowledge about the Hi-Power.
Other guns to check out include the Glock 19 and Walther P99, with honorable mentions going to the Sig 228, HK USP and HK P7.