I would pick Larue. If I needed an uninterupted top rail for whatever reason and HAD to use a conventional reciever, I would get a VLTOR CASV-EL but it will limit the types of optics/mounts you can use.
If price is an issue I'd go MI or go with plastic handguards. Just remember "buy once cry once". Don't go buy the cheapest red dot, flashlight, rail system, iron sights, bolts, etc. just so that you can have that stuff on your rifle RIGHT NOW, that money would be much better spent on training, ammo, and practice. When you take classes to become more proficient, try other's equipment out yourself before you decide if you really need it. Don't get caught up in spending all your money blinging out your rifle to the point that you can't afford ammo for it.YMMV.