Wife's got 105s, I have Rival, used to have an older Ultegra. I think they are both great, but I really love my Rivals. Once you get used to the single lever doing all the work action, it's just great. I've had 0 problems with it, none, and mine's a 2008 (I heard they are better now?). At the end of the day, I think it probably comes down to personal preference, but forgetting potential pricing differences (no clue how they compare in cost), I'd go Rival.