Which games had really well thought out and engaging leveling system?
Skyrim was a good baseline I believe, not perfect but engaging and not too punishing. Path of Exile seems convoluted to me, to many skills the dont make any real impact. Fable was effective but very simple. Oblivion tried hard for a deep leveling system but was basically broken. Witcher 3 was pretty run of the mill (I thought, despite the praise the game gets).
I'm trying to find something where there are several viable different playstyles. And it's always good when combat isn't the only way to proceed.