IMHO you should look at what you want to use the pistol for and make your decision based on that.
1911's are great, but it's not the best pistol to use for SD if it's your first autoloader. Consider this...........lots of people make 1911's there's no set "milspec" that you would look at like you would an AR15. So some will work better than others and parts are not always interchangeable. Cost goes from well under $1,000 to nearly $3,000 if you look at Ed Brown, Les Baer, Wilson Combat. If it's primarily for plinking, target shooting, etc. I'd suggest this. Longer sight radius, better trigger will probably lead to better results. Heavier weight (unless you go with aluminum frames) will generally mean less felt/perceived recoil.
Sigs (P220) are good out of the box. The triggers are not going to be as good as the 1911, but definitely better than the HK. If you are looking into SD, then I'd opt for this. No safety, long double action trigger pull transitioning to a single action thereafter. Of the three this is going to have the most felt/perceived recoil.
HK USP or 45. Worst trigger of the three, but will still shoot well. I personally think that my USP shoots softer than my P220 and P220 Elite, but not as soft as my 1911. I shoot my USP better than my P220, can't say why, I just do. I don't own a HK 45, so no comments on that other than when I shot my friend's I really hated that groove that is cut on the top of the trigger guard. I hate it so much I'd rather shoot a USP than the newer 45.
Finally I would suggest looking at an M&P 45. With the modular grip you can best fit your hand. With a trigger kit, you can upgrade the trigger. With a different spring you can tame out how snappy the stock pistol feels.
Best thing as others say is to shoot them.