I don't tend to play rock/blues//metal/anythingwithdistortion, but I have never been able to find any love for the MicroCube. The JC-120 setting (or whatever it's called) sounds decent enough to me, but even that is kind of average to my ears. Naturally this is all just a bunch of my mostly uninformed opinions.
I've had good Vox valvetronix amps, and I have a well-known love for Super Champ XD/2s. The new Yamahas seem to have some love, but I have no experience with them. For a portable headphone rig, I am using Jamup on the iPad and am impressed.
So, Super Champ Xx.