5Dimes has the edge over Bovada when it comes to competitive betting lines but their app SUCKS big time. Those guys must have made millions over the years from US sports bettors and they've reinvested none of it into developing a decent iPhone betting experience. I would use the 5Dimes app a lot more if they would only develop something similar to what Bovada have. The BetOnline bookmaker app is nothing to get excited about either but it's not bad once you get used to it.
CloudBet is probably the seconds biggest bitcoin bookie after Nitrogen Sports. Their mobile app also works great on iOS/Android. Read about it here.
The most popular is William Hill and I have no doubt about that. You can bid on sports whether basketball, tennis, football, rugby, boxing and many more. This app looks like other standard programs where you can bet on specific result. If you want to make money on the sport side then William Hill is one good opportunity to try. Aside from it, 888 Sport is a must try app too.
Nitrogen Bitcoin is a good app. My brother uses it from Australia. And he is quite satisfied with it.
Yes, Nitrogen Sports is quiet good but my biggest issue with them is the lack of in-play betting options. I usually have to wager at Bovada or CloudBet once a game has started.