That's a question that is tough to answer--everyone will have their own opinion, and not one suggestion will be absolutely correct for you. Personally you can't go wrong with any of your choices--I have all three and enjoy each one of them. Probably my personal favorate is the HK USP--I just shoot it the best, and I definately like the safety and the slide release the best of all three. The downside is the mag release--takes a little to get used to if you're a 1911 shooter. I have a USP Compact in both 9mm and .45--love them both. Neither has ever had a single failure to feed or fire, but the same can be said for my SIG and my 92FS. The HK is the most expensive, the 92FS the cheapest. Another option would be a SIG Pro 2022--I have one and it shoots as good as the 226 at a few hundred dollars less. The 92FS is probably the most pleasant to shoot, but also the heaviest. I'd start with one of them, and as you can add the others to your collection.
"Adversity does not make a man--it reveals him"