i say the ar for sure.
and bushmaster, rra, dpms, any of those makers are great and will serve you well. i have a bushmaster and owned another bushmaster in the past and have experience with many many other bushmasters over the years and they have all been great, the two that i have owned are good shooters eat anything and i never had a problm out of em.
the ar just has so much going for it and has tons more accesories and after market stuff for it. plus just having one is one awesome feeling!
ar's are or can be made totally modular and you can stick about anything that your heart desires on there, depending on the application that you want it for.
i suggest a a3 model with flat top, 16" m203 profile barrel, and a nice muzzle device the standard military birdcage is great, i also like the phantom and the vortex as well, my bushy has the izzy on it.
i don't need many ar's but i want a 9mm model. a spr model, and sdm set up and a regular a2 20-" barrel set up match if possible, and i woul even love to have one of the dpms sass in .308, do i need them no but wanting out ways need in my book when it comes to firearms.