I am using Nitrogensports.eu for my sports betting now, the sports odds offered by them are acceptable for me, and my withdrawals on the site are always processed without any issue. Sportsbet.io is another site that I used occasionally, but I have seen some high bettors having issues with them on big withdrawals, so it might not be advisable to use sportsbet.io if you are planning to wager huge amount of bitcoins.
In the past I have been into directbet.eu, and once they stopped their service moved towards nitrogensports.eu and this is quiet good for sports betting with better odds and therefore is no flaws in the settlement of the winning amounts. Not sure of sportsbet.io which I need to give a try.
Make sure to check their feedback before trying them out as those are left for a reason.They have involved in various scam activities from faking promos to making their shills win the competitions.After the end of directbet ,I kinda gave up on bitcoin sports betting.
I agree, try researching first about the gambling site or sportsbook you are going to gamble on before you bet there. That would be the best thing to do first and not really go all in on that site. Or just use the most trusted ones like nitrogensports. I believe big sports books like 5dimes and bet365 accepts bitcoins already.