If "mismatched" cranks bother you that's a sign that you are looking at your bike more than you are riding it.

I had some MegaExo cranks. I got some more use out of them after the left arm started coming lose by using a Loctite formula that's made for filling gaps between parts. 600-something is the number. The regular thread lockers don't work for this purpose. It worked but was a hassle.

I put some Rival GXP cranks on that bike. The GXP cranks are easy to install and unlike the FSA cranks there is no way for the bearing preload to be wrong. I have GXP cranks on all three bikes and they all spin very smoothly. I have not yet had to replace a BB bearing, unlike the FSA cranks whose bearings did not last long.