As an American, I like the legality of fantasy league. Fan Duel offer more contests with the bigger prizes but the rake is higher.
I didn't fare well because if you don't pick everything perfectly, you end up on the short end of the stick. The two reasons why i played there was for "action" and the possibility of big prizes. Let me tell you folks, even 10-20 dollars per day adds up.
I went to Draftstreet. Their prizes are lesser and unless you're in a small league, there's less opportunity. With Draftstreet, you have to master the way that scoring is processed. Points (scoring a basket) aren't the most important approach in choosing a player. You want an all around player. If a star player like Joakim Noah scores 9 points, you can still have a good score with the rest of his production.
Draftstreet also tells you how much "time" (players remaining to play) that you have left on your roster for the night in comparison to the rest of the competitors. The overall layout is so much more professional than Fan Duel.
Now I'm not saying "don't choose Fan Duel" because sometimes people need action. I'm just saying that Draftstreet gives you a better chance to win and I feel like my money is safe there.
Good luck. Take my approach. I guarantee you more success.
BTW--I've had more success in 10 Draftstreet contest than 100 Fan Duel ones(Fan Duel is like a lottery ticket)