The one I am bullish about is $PCX they will certainly get in and they will be the link between $BTC and $DOT and also other crypto projects.
This is massive and they are not very known yet even though they are mentioned on the front page of the Pokadot website and the CEO of $PCX (Chainx) knows the CEO of Polkadot very good.

This is the one I believe in but please DYOR