I should start by saying, get out and demo ride some bikes. I only "discovered" the more slack angles of the Stiffee by accident... But I now love the feel of the bike. I find it very forgiving when I try something that in reality is well above my ability!
Cove Stiffee is a frame only option; you will have to select your own components (which is not difficult but can be a minefield - I had enough knowledge to know how I wanted to build up my Stiffee).
Plenty of good quality bike shops will offer you a custom build option. I actually built the stiffee myself with the exception of Bottom Bracket, wheels and headset. My first foray into building.
HT of your choice
XT groupset (although SLX is now viewed as the new bench mark MTB groupset)
Fork of your choice (lighter air ranging to heavier coil: QR or bolt through options). Personally I'd go for a Fox 15mm bolt through Fork.
Wheels (Hope hubs plus Mavic IMO good value for money)
Finally I commute 18 miles return each day on the stiffee. However I do also fancy a hack bike for the commute.