either one will be fine. you don't need any options. if it's a flat top, obviously you need a rear sight or carry handle. otherwise everything else is just extra.

you should also check out rock river arms, stag, cmmg, etc. you should be able to find an entry level ar for at or around 800 complete. the problem is EVERYONE is buying them because of the election so you might end up with a month or two wait.