[Kameron8]

I don't have enough recent experience to comment on Summoner power compared to other classes, but I agree that your premise is correct. Seiryuu is almost inarguably the best Youkai on average, for the reasons you've listed. A vast swathe of the other Youkai lack the stats to either survive a stiff breeze, or present no danger on offense.

I also agree with your conclusion, that a hefty rework to Youkai stats would promote variety. As a personal opinion, I believe if there were more limitations on how many Youkai you could ascend, that too would (eventually, when enough are released) allow key differences in each Summoner's arsenal.

What I don't know, however, is how anyone would be able to fight against Summoners if everything they summoned was viably powerful. As you already mentioned, it's difficult surmounting the skewed action economy when fighting Summoners. Because of that, I don't see how every Youkai could be given sensible stat lines without other reworks that reallocated Summoner power.