I think Kohli is further ahead of the competition in limited overs than Smith is ahead of the pack in Tests, so overall I would probably have him ahead, but in Tests Smith is comfortably the best bat of the generation. I think they're both equally limited captains though (although Kohli hasn't managed to drop a nuke on his own side yet, so I'd have to give him the edge there as well).
Perfectly summed up. Smiths test avaerage of 61 and Kohlis record in ODI and T20s backs up your case.
Their win loss draw records as captains are similar as well. Also their batting averages as captains says they’ve stepped up; Smith 70 and Kohli 65