I own or have owned all 4 of your mentioned pistols, OP.
I USED to own a minty G17 and a pile of mags.
I USED to own two different Steyr M9-A1 pistols.
And I USED to own a 4" XD Service in 9mm.
I STILL OWN two M&P FS.
I'd take the G17 and that pile of mags back, though, just to have around.
The Steyr pistols: Great guns. What Glock would be if Glock grew up (same designer). Parts, mags, and accessories aren't easy to find and aren't inexpensive when you do. GREAT ergonomics and a very robust platform.
XD: I don't like the feel of recoil in the XD platform. They have very tall slides which leads to a lot of reciprocating mass too far above my hand/wrist to be comfortable. They're also single-action guns with a grip safety. Being SA doesn't bother me as much as having a grip safety does.
My vote: M&P.
I USED to own a minty G17 and a pile of mags.
I USED to own two different Steyr M9-A1 pistols.
And I USED to own a 4" XD Service in 9mm.
I STILL OWN two M&P FS.
I'd take the G17 and that pile of mags back, though, just to have around.
The Steyr pistols: Great guns. What Glock would be if Glock grew up (same designer). Parts, mags, and accessories aren't easy to find and aren't inexpensive when you do. GREAT ergonomics and a very robust platform.
XD: I don't like the feel of recoil in the XD platform. They have very tall slides which leads to a lot of reciprocating mass too far above my hand/wrist to be comfortable. They're also single-action guns with a grip safety. Being SA doesn't bother me as much as having a grip safety does.
My vote: M&P.