Here's my take, from an admitedly limited perspective.
Functionally....
LMT & Colt are high end.....
then there's a large number of manufacturer's in the middle.
then there's some enonomy manufactures, like Olympic, Del-Ton, etc...
It seems like both Bushmaster and S&W are both squarely seated in the middle class, perhaps the UMC.
Howerver, S&W are reported to have tight mag wells.....have read reports that P-mags do not work in them. P-mags are probably the most popular and reliable mags.
Other consideration.....
Bushmaster is up in Maine (a free state....where I am). I doubt you'll find an anti within 20 miles of Windham, ME, where Bushmaster has their facility. Bushmaster has never sold out the R2K&BA community.
Smith and Wesson is down in Massachusettes......one of the biggest anti states in the country. You can read up on S&Ws iffy track record, appeasing the Clinton admin. to save their own necks.....right up their with Bill Ruger in many peoples opinions.
You decide which economy and which company you want to support with your dollars.
so I'd say support the