I agree with Simmo.
Sports you could be watching a game at a bar or at the match and place a bet easily. The time it would take wouldn’t be much. Casino I would put 2nd on the list since you can play and if you get a time out I don’t think it would be as big of a deal, either you wait for the hand/slot to be processed or you come back at it later. Poker on the other hand I would find is very risky. If you ever get timeouts or occasional internet problems playing on your pc imagine your phone dropping out on this.
Last you have to also imagine how and where the user would want to gamble on their mobile phone. Sports it is just too convenient and requires little time. For casino requires more concentration and perhaps this is an activity someone could do at their work office or in transit. Poker requires too much concentration and something you wouldn’t want to drop a hand over so perhaps you would see this happen less at the office. Unless they are playing for fun then I don’t know but either way you would have a game where more players would be timing out and coming & going much faster.
John