Should i buy Cardano or Avalanche?

Should I buy Cardano or Avalanche? I've been following the cryptocurrency market for a while and I'm considering adding some more coins to my portfolio. Cardano seems to have a lot of potential with its focus on scalability and security, while Avalanche is making some interesting advancements in decentralized finance. But which one should I choose? I'm not sure if Cardano's technology is more advanced or if Avalanche's ecosystem is more promising. Can you help me make a decision? I'd like to hear your thoughts on the pros and cons of both projects, as well as any predictions you might have for their future performance.