New guy here planning out my first AR build and I've run into a small dilemma.

I'm pretty much set on a Mega Arms billet build, but am having trouble deciding between the following;

- Mega matched billet upper and lower + DD 9" Lite rail - @ $710-$730
- Mega billet lower + Mega Monolithic upper - @ $775

I'm not too concerned with the price difference, but it is there. I worked out the prices mostly from Rainer Arms and Riflegear.net. Riflegear lists a preorder price of $584 for the midlength Monolithic.

The rifle will be used for the range, defense, shtf and training. I'll be buying a stripped barrel and an AA gas-piston kit as well.

Basically, what would you buy (and why) if someone gave you $800 and the choice between the above two options?