Any clans that can complement Vortex's weakness is pretty good. What are some of Vortex's weakness? Weak to SOA, low base damage, not "solid" (in winning rounds, etc). Some good clans that work pretty well is Uppers, Fang Pi Clang, Nightmare, Ulu Watu, etc.
What cards you choose for your Vortex will also affect what cards from other clans that compliment well in your deck.
If I recall right Vortex lacks a solid SOA and reliable damage reduction (C Wing opens up opportunities for KOs or +pillz/life per damage while Neloe has min. 3). Maybe something that can cover that like Sentinel?
If you have an aggressive matchup (X-0DUS, C Dusk) you might want a bit of defensive cards to match that up. Pussycats is one, Roots is (was?) another. On the other hand if you go more conservative with cards like Cyb Lhia or Dagg/Deea, maybe powerful cards from Frozn will work out well.