Right now I think it's consensus (or at least majority opinion) that mining/savanna are overpowered even though people disagree in the ways they are. But clearly, some things are underpowered and need some buffs.
Quoins are a bit underpowered right now. They're pretty much useless beyond level 5. I think this comes in part because we have very few "high level" areas -- nearly every area in the game is accessible to anyone of any level, so when you're level 20 almost every quoin in every area (save maybe the Savanna) contributes virtually nothing to your XP/Energy/Mood.
Anything gardening and animal-related are pretty underpowered, nevermind meditative arts. The bonuses are nice and the buffs from herbs are good and the energy restoration from focusing is convenient, but very few strategically-minded Glitch players will see gardening as a viable alternative to mining, or even cooking. They won't make it their thing. Right now, anyone who wants to advance quickly in the game will get mining ASAP. I'm relatively new so I could be wrong about this, but that's pretty much the consensus I've gotten from when I've asked, anyway.
In any case, this is just what I've noticed -- if you have an opinion, differing or not, please share it.