1911, Sig P226, SA XDm, Ruger GP100, and a CZ 75b would all rank high on my list of suggestions. You can also build a pretty decent AR15 for $800.
Leaning toward the 1911 isn't a bad idea. But I might set my sights somewhere other than the Ruger SR1911. I actually have one, and it's a solid gun and a looker at that. But they're awful tough to get your hands on at the moment. While mine is nice and tight, I've seen a couple recent examples with an unacceptable amount of lateral slide slop. So if you do have a line on one, please do take time to inspect it carefully before forking over your $700.
My dealer's been getting customers the Remington R1 Enhanced
for $750 or so. You can also get into a Springfield Mil-Spec
in whatever finish you prefer for under budget. Those are probably the first two 1911s I'd look at in the $700-800 range.