I can't comment on the Bushmaster as I've never owned one or shot one. They tend to get up and down reviews since the Cerebrus buy out a while back. Windham Weaponry is the "new" Bushmaster and was started by the guy that started Bushmaster who bought his old factory back and hired most of his staff back.
If you get something without optics and a railed gas block, plan on getting an iron sight which can be pricy. Minimum $100 for a front and rear on the cheap end.
Others have recommended the Smith M&P Sport and I'll back that 100%. I have the M&P OR and it's been an outstanding AR. If you look around, you may be able to find out for about $600. It's worth the search.
As for Palmetto and Spikes, both are also great companies. I have a Spike's AR that I built with a Palmetto lower build kit. It's just as much fun as my M&P is to shoot but came with a front sight block.
Best of luck in your search!