I liked the original Ori the most. I've played it so much that I've gotten all achievements, including the no-death and under 3 h ones.
The definitive edition added the much needed teleports between wells, so that was a great upgrade.
The sequel lost some of its charm imo. I didn't like that Ori is now slashing with a sword; I preferred the original's approach of Sein being the damage dealer.
The final battle in 2nd game was a huge difficulty leap imo. Falling down was really not fun.