Hallo Lornyy and welcome on the PokerStrategy forum
You should take a moment or two to Introduce yourself! to us properly.
Regarding your question, I think it depends on you. If you are completely new to poker and would like not to reload money again right away, but keep playing with your starting bankroll, then I think I would take the FREE20 one and play the smallest limits. NL2 if you want to play cash games or 1 cent to 1 dollar tournaments or SNGs. If you already have some experience with poker and is okay with the varians, I think there is more value in the THIRTY bonus. 
Also it looks like your still a basic member on PokerStrategy - you can use 1 or more of our free money offers on poker rooms you don’t have an account yet if you are interested in that.
Further I wish you a pleasant stay on our forum and if you have any questions don’t hesitate to ask them.
Best regards,
Malendes