I dont use Olympic,but I looked them over and BETCOM seems to be better....plus what I like is that with betcom if you deposit by western union(which i do) they cover the transfer fees for $100 or more...most books you have to send $200-300.
Plus with betcom you have LIVE HELP where you can chat online with the cs reps and dont have to wait for an email reply.
BIG thumbs up to BETCOM here....if you want to join,let me know and use me as a reference.