Nitrogen and betcoin are both excellent...i would also add Fairlay as they have the best odds plus fast fast payout...fairlay is also interesting because they have a user danhan11 who has created an app which allows for parlays..it is currently being tested w positive results so far..
For agents accounts i had been using AC88 and still do they are excellent but a new one odyssey88 i have been using too and have experienced greatness from them...very fast btc withdrawals and excellent customer service too w similar bookand exchangesas ac88..they do random kyc if any suspicion occurs like multiple accounts like AC88 or any book do so make sure u give verifiable info...