the question should not be "what do you want more" but should be "what do you want less".
To me, cubieboard (1 & 2) has a perfect form factor (60x100 mm) but i understood that more power can be needed.
Nice to me will be upgrade of CPU, (maybe a 4 core?) but foundamental is to AVOID ABSOLUTELY passive dissipartors or - worse - fan for forced air recycle.
to me, the key point od a embedded board as cubieboard is the not need of dissipator/fan. A20 is borderline because it can get too much hot than i wish, so we should do pressure on ALLWINNER to do A20 with less nanometric geometry to make A20 more fresh at same clock speed.
All board that force end user to adopt fan will never get in my house:
All board that need of passive dissipator is VERY bordeline to make me to refuse a board.
for these reasons Cubieboard A10 is my favourite board.