Centra and TenX are certainly the top two.

Both have received excellent funding, and have good teams, and have working cards / cards ready to market.

If you're planning on getting cards alone, get both.

If you're planning on investing long term, split your investment. TenX prices have fallen so it is a good time to spend on it.

If you're planning to invest short term, I'd say put all your money on Centra. They have a working card which they're distributing, and have generated enough hype for their ICO for it to get sold out quickly, which means there will be demand - which will lead to a price boost.

This is not investment advice, just my observations.