I really like this question actually!!!!

okay so i think the best ones are (in no particular order):

1. stamina recovery by turn and participation
   very few cards have these ones but in 4th anni set like 5 of them have by participation. and also 2024 bday bradley has this skill so i kinds regret not having this card
   by turn only 2 ssr cards have it but at least they're in the normal gacha pool so you might get them someday.

2. chance to increse ALL parameters
   not much to explain here, pretty self explainatory. very useful. singular parameter increases are okay but all parameters is the best obviously

3. training great sucess chance
   also pretty easy to understand and pretty common

4. chance to add parameters at the beginning of the turn.
   this one is really useful when trying to get a max chibi but then every wizard should have this skill with all 5 parameters.