For combo versus head, on the Egnaters, the heads have the dials on the front, the combos on top. No biggie really. Just easier to use the head when on a mini-stack. I went with a Rebel 30 head rather than combo cause I am getting old and jam at some places that have cabs so instead of hauling a combo and an extension cab (in my case the Peavey has restricted cabs you could use), I can now just take the head along w/ my pedal board. Less to move around. Heads probably give a little more flexibility in terms of types and arrangements of cabs that can be used but I know there are lots of folks on the board that have way more experience than I and can probably provide better info on that.
I also just looked at the Carvin's that KC pointed out. One thing I find that was limiting is having a single output impedance for cabs. A head will often give you 4, 8 or 16 ohms with two jacks whereas a combo often only gives you one selection. Not always true, of course. My Egnater Rebel 30 gives all three. My old Peavey was limited to a 16 ohm extension cab. Something else to consider.
The river keeps a talkin'