Who wins?
Stacking a +4 on a +2 vs 7-0 rule
Stacking a +4 on a +2 wins 52% to 48%. 81 more put them in the same row. From Board Game Rule Debates Tier List. Pick a side.
retired_pickle on Stacking a +4 on a +2: if you allow stacking, color doesn't matter
GoldenPickle54 on 7-0 rule: it's an official Uno variant, it's legit fun
Board Game Rule Debates Tier List: the full ranking