A pretty common line you hear when discussing Steyrs is that the trigger "is everything a Glock should be". Alagator summed up the pro's/con's of Glock and Steyr already.
With regard to HK, I am also an HK USPc .45 owner and if push came to shove and I had to return one of the pistols, my M9A1 would still have a spot in my safe. I think the guns are absolutely comparable in quality, but the Steyr's trigger infinitely better and is, overall, more fun to shoot.
In the Sig vs. Steyr debate, I would unfortunately have to give the hats off to Sig. I like my Sig more than my Steyr, but it's all a matter of personal preference.
I think Steyr is about the best bang for the buck combo on the market today. Any time someone wants a helluva pistol without breaking the bank, the M-A1 series is my first recommendation.
And our little community is growing - ever since Steyr Arm's advertising campaign in NRA magazine publications, it seems like Steyrs come up almost weekly on the 6 other firearm forums I frequent. I'm a firm believer that Steyr will achieve the same brand familiarity as the other big boys you mentioned in the next few years... Keep your fingers crossed :wink: