Which one is better?

For versatility, Khalifa or Kai from Galaxy Girls are good, but Girls Monsters will be rarer, hmm. If you want stable performance, I recommend Galaxy Girls, and if you need unique cat combos, I recommend Monsters. Since it's a guaranteed pull, think carefully.

I think there were characters with high potential but low floor, so maybe wait for other banners to drop and pull for different series. I'd recommend Hell Onma, Gods characters, or Gryphon.

If it were me, I'd pull for Girlmon first. The reason is that it's a banner series that gathers characters who don't appear in events like the Cat Festival or Platinum Tix.

If you can't 4th evo, you can skip them.

I recommend not pulling for either and saving for the collab or the Lunar New Year/Anniversary banners instead.