i'll go with thisPost-Dangai Ichigo has more reitsu, but Yama has better abilities.
Someone with less reitsu can defeat someone with more. Was shown before Ichigo even went to SS when Byakuya owned him and after he sad Ichigo had more than him. So reitsu doesn't mean everything if you don't have the abilities and experience to go with it. Yama's thousands of years perfecting his bankai, gaining experience, and his fundamental abilities > Post-Dangai Ichigo. However in reitsu Post-Dangai Ichigo > Yama
All in all though Yama would win a fight.
The statement about Yama being the strongest Reaper alive was never contradicted. Even considering all of the power and hax Aizen had he made it a priority to seal Yama's flames because he was intelligently scared/worried about Yama.
Also, when Yama said in the last chapter that Ichigo still has a lot of abilities and his bankai is simply not at it's 100% poptential backs it up too.