I've got 2 RRA's.  One M4 and one midlength with an A2 buttstock (may change it to collapseable but not sure yet).

I want one of them to be iron sights one of them scoped.

The scopes I'm condisering are an IOR 3X25 QR-TS or a Leupold 1.5-5x20 Mark 4 PR.  These are essentially the same price.  I also saw a good deal on a used IOR 1.1-4x26 CRT with a YHM rail and Leupold QD rings for the same price as the other 2 options.  I'll probably stay with new stuff but I'm also considering the last option.  I don't want reccomendations for other scopes than the one's listed.  If I went with the Mark 4 it would be mounted with the hi riser mount w/integral rings RRA sells as I have an extra one.  There's a pic of this mount below.  I know it's not the best but it works good for me and I can't afford LaRue.

Basically I'm trying to decide if I should have the M4 with the scope and a decent BUIS, or the midlength with the optic BUIS and a Harris Bipod.  I wouldn't put a bipod on the M4 as I don't think it leaves enough room on the handguard because I don't like foregrips.  Is there a reason one would be better as a plain jane iron sight rifle?  Would the Midlength be served best with the A2 stock or collapseable?  There's just to many decisions for me.  Please help!!

I would keep the M4 iron sights, and scope the midlength.

ETA:  Oh yeah, keep the A2 stock on the one you scope.  Chances are you'll want body armor for CQB therefore might need the stock to adjust to it.  The scoped rifle will be for distance, so you more than likely will not need any type of body armor, unless of course your a counter sniper i suppose...

I won't ever probably have body armor .  Just your average dental student arm chair commando.  I may start shooting in some competitions at the range I'm a member at.  I just like to setup my rifles as if I would need to rely on them.  Kinda silly I know but I feel the need.