I hate AJ the most because of the story and characters, but I1 is without a doubt the most boring game in the series (although 4-3 and the first day of 4-2 are up there too). Ultimately, I'm still more offended by AJ as a package deal than I am by I1, although I'd sooner replay AJ than AAI1. Even just thinking about I-3 and I-5 makes me feel dread within me. Still voted AJ because I hate it on an emotional level.
GAA1 is a ridiculous answer. I'm not a huge fan, but even just based on the rather amusing script and pace, it's infinitely better than either of those games. It does feel like an incomplete game, but I'd sooner play any of the GAA1 cases anything in either AAI or AJ. So many of the GAA1 witnesses are fucking hilarious.