In my opinion, a Sept calf would be more competitive because it is older, and thats what I would chose. (the oldest heifer in a class, usually wins around here.) I think that chosing a fall calf (born in sept. 06) would be a great choice for your daughter because she can train her while she is young, and then bring her back next year as one of the oldest heifers. Around here sept-dec class is also a lot smaller than traditional spring born classes. If you are looking at an 05 fall calf, than she will be a senior yearling this year, will be big, and better be trained when you buy her. (or she's gonna be trouble) If you are looking for any age heifer, January/March calves usually compete well.