Hey Dana,
I have tried a few of them...
Twinspires in my opinion has consistently outperformed all the others. They take a lot of tracks. They allow you to review all your bets online whether you placed them on the phone or online. The Video Quality is very good. Their rewards program is okay but nothing special so that is my only gripe. They also partnered with BRIS so if you use BRIS PP's it is free for the tracks that you place a wager on. Phone access is pretty good except on big days where there is usually a pretty long delay but the online connection is usually good on those days. They charge a flat $5 fee for online deposits using Credit cards and no fee if you use their ACH service and the money is available in your account immediately. They also have a lot of contests that they run and special promos where they pay you 10% over the payouts if you hit a bet.
There was an issue last year when they took over another big company and there were a lot of delays for a while when calling but it seems they have fixed all of that.