I can agree with that.
This wasn't the case before the Venom movie, however, I will concede Venom was more well known than Ahsoka before first movie/show appearances.
I think Mandalorian did more for Ahsoka than the Venom movie did for it, in terms of exposure.
This is absolutely false. We just didn't see her coming into the big picture anytime soon.
Same can be said of Venom compared to it's comic book version.
At current prices, I don't think either is a "good investment". The market is skewed right now and there will be price corrections but if I had to choose one, Clone Wars is certainly the better bet, considering the sheer amount of copies of ASM 300 out there.