Lots of cake flavor is good, doesn't really have to be buttery but it has to actually taste like cake or cookie, not like weird stale sponge cake. I tried Ahlusion strawberry vanilla cake before and that's what i thought their cake note tasted like and I did not like it. I could have gotten a bad batch since so many people seem to love them but I'm wary to order again.
I'm not a fan of the Strawberry or Blueberry Vanilla Cake for the same reason as you, but I really like the Lemon Vanilla Cake. It's like a lemon poundcake. Much better in my opinion.