4* Tech rank up-

GQuantao

Already have Ultron 4* R5, (have 15 5* heroes, None of them tech) I'm not great at maintaining long combos so I'm leaning away from SL. Please give reasons as well

p.s.- Vision is sig 40, and I just pulled a Vulture also, he any good for AW defense?

Hollowborn

Vision and his bleed/poison immunity is extremely helpful for questing/events, not to mention his power control.
My Vision is 5/50 sig 99 and he's been a very reliable toon.
I do recommend SL too though if you can start practicing your combos.