I have an AR15 upper laying around and I'm going to acquire another lower to make a "precision rig".  I need a good trigger for it and I'm leaning to using a cartridge style trigger set at 3.5 lbs.  I'm looking at this one in particular -

CMC  3.5 trigger

For "precision" I favor a 2-stage, but I've tried that trigger and it is pretty nice for a SS

SSA or G2S

Larue MBT is the answer you seek

Wilson Combat- TTU = $190 for a drop in. 3gun is the 2 stage 3.5 lbs.
The Geissele is not going to perform any better for 20% more $.

This

Kind of odd timing, asking this question, don't you think?

Because why?  You think I'm going to attempt to assassinate a former President?  What are you?  Retarded? ??

Geissele SSA-E

Geissele SSP. I replaced a CMC with the SSP. Much better.

I have that trigger in my .308 that I use for deer hunting and what not. It's a nice trigger for breaking a shot right when you get the crosshair on target. My honest opinion is it's a little too light for heavy gun.

I love CMC 3.5s.

But, for a precision role, I lean toward 2 stage triggers as well.

My current precision gun lineup use Schmid 2 stage and Geissele SSAEs.

MBT2s. I have one of the CMC 3.5's and it's better than a stock mil spec, but I'm honestly not thrilled with it. I have an MBT on another rifle and it's a much better trigger for the $.

I've had a couple of CMC 3.5s (still have one). I like them we'll enough, but if you're building this to be a precision rig, I think the SSA-E is the better option. I know you said a cartridge type, but, that's where I'd spend my money. The votes for MBT are good too, if you're trying to save a few bucks, but the E is nicer.

For precision the only answer is G HSNM.

Not sure why anyone would recommend anything else.

Perhaps a "precision" rifle is a bit of a stretch.  It's not going to be super long distance, just a AR with a 4-14 x 44 PA scope in a PA mount that I'm picking up from the EE.  I just want something that I can reach out beyond what I can hit with my other AR that has a red dot/ 3x magnifier.  THAT rifle has a CMC/Lantac ECT-1 trigger, 3.5 lbs with straight shoe.

A friend of mine likes my trigger so much, he doesn't want to shoot his DD rifle that cost him 2 grand

Yeah I know that's a lot of scope, but my eyes are really getting bad, and I need the extra zoom to see at distance.

IMO there is a lot to be said for having the same feeling trigger in every rifle you have.  I like two stage triggers with a 3.5 pound pull.  I have them in every AR or LR rifle I own, be it a 6.75" .458 SOCOM, .470 Rhino, or a .223 HB target rifle and down to several AR-22s, both rifle and pistol, and a heck of a lot in between.  No matter which rifle/pistol/SBR I grab, the trigger pull is the same, they pre-load the same and break the same.  Most have the RRA 2S NMV trigger but the last dozen or so have the Midway Stoner (Schmid) two stage with the JP yellow trigger spring.  All have a 3.5-4 pound pull with the first stage being about 2 to 2.5 pounds and the second stage about 1-1.5 pounds.  None are over 4 pounds and none are lighter than 3.5 pounds.  To my fingers, I cannot tell the difference between any of them and all, every single one, has proven to be 100% reliable.  There is nothing I loath more than picking up a rifle and having its trigger feel different than all the others.  Sure, my bolt, single shot, and lever guns have different feeling triggers, but when I pick up an AR/LR I know exactly how the trigger is going to feel.  IMO, go with another trigger like the one you have.  No surprises that way.  Of course, YMMV and I can only speak for myself.