ASUS and AsRock are no longer affiliated with each other. Last year there was a split AsRock name is now owned by Pegatron and are actually competing against ASUS now. With that said they used to be crap back in the day but have really come around in the past few years. I have recently built systems with both ASUS and AsRock boards and have had no problems If I were you I would just pick the one that has all the features you are looking for, and fits in your budget.
I've bought at least a handful of ASRock boards over the last few years, and none have given any problems.
BUT, to answer the OP's question, if at all possible, wait for AM3+ boards to be released. There will not be any more powerful CPUs released for AM3, but AM3+ will support Bulldozer.