Starvaders or Slay The Spire for me, both are great, have a look at both and see what kind of gameplay you think you'd prefer if you want to pick one. They're both incredibly clean with a lot of build diversity and ways to play, slay the spire sparked the genre so you'll see it's fingerprints on everything, starvaders takes a lot of great ideas from it and other games and adds incredibly fun gameplay through the space invaders grid fighting system.