Kamigawa: Neon Dynasty Chief: Im going to have to go with Boseiju, Who Endures , even though this set had a lot to choose from
While there are some more collectible serialised cards, dont expect to have anything close to a One Ring situation with this set
If you are getting card advantage out of discard effects then Hymn is the best of those because it costs you the least tempo
This is something you can do in green ramp but it requires some work in the build and may not be supported well in the cube you are playing
This means that each instance of damage, whether it be combat, activated ability, or spell, will either cost an additional mana or two life
Blue can draw the most, sure, but it also has many, many redundant effects and cheap options on the curve that can do other things