My least favorite is Rescue Cat-Airbellum. It's just so cheap! You get one certain monster and you automatically get a Synchro! My favorite is either having two solar flare dragons and using lightning vortex, or Exodd, Sword and Shield, and Lightning Vortex. As you can see, I'm a huge fan of Lightning Vortex.
Favorite/Least Favorite Yu-Gi-Oh Combos
Just use the General Yu-Gi-Oh thread.