Keep playing Kaiser?

The only other option is flavor of the month classes, which is currently shade. He will get the same treatment your kaiser did. Enticing at first, but when you invest into it he will be nerfed/the drawbacks will probably become unbearable.

That pomegranate "class" never got nerfed, and I don't get why people (in gms at least) like it, but whatever.

Also on topic I would keep playing Kaiser it has great mobbing after the "star force" update, along with the nice survivability it already has.
I would just invest in "Rude" sword if I were you, for much greater damage overall (1>2 hits on wingbeat), which would make the % go up by alot.

Overall Kaiser's greatness overcomes the cons, along with the buffs later on which will make the cons a bit less noticeable *cough* sword strike in transform *cough*, about the stance part though maybe you should invest in a Mikhail link skill it can help when your gauge is low, or you could use the command or w/e it is called in gms for faster gauge charging.

Demon slayer is pretty good as well especially after the "Insult to injury buff", and it has everything you're looking for, I'll say give DS a try.

Even though in the end I would say Kaiser is much better with all the changes it's going to get and such, and I wouldn't exactly say that thier damage is low .