Lazy Cap would be the best for PVE, but you really need that 5th red. If you are looking for depth in PVP I find my 3* covers at 127-140 still play really well especially when buffed.
For who you have I would say Cap or HT. HT would pair well with Hulk especially if Hulk will tank for HT and build more green. Cap will be better for PVE, and IM40 if you boost is very good with Cap.
Since you have two R/G/Bla max’d, I cant endorse HT.
BW is nit worth leveling before getting 5 green
IM isnt worth leveling…
Daken and BP are good… But the covers are an issue. Especially for panther. He needs at least 4 black.
Cap and Daken are your best options. I like daken since he will work well with your current max’d. However, cap is more cover ready.
As soon as you have enough iso to level the 3* over 100. 9 covers will give you a soft cap around 114 lvl. So in general, its not helpful to spend iso on any 3* with less than 9 covers. You would be better off stockpiling that iso or max raising a 2* roster.