I like the Arthur swimming one, the magnifying glass one, the one with the kids "hatching" from the center circle, and the hot-air balloon one with the kids and Mr. Read.
I am a little disappointed that they replaced the original title cards with scenes from the episodes. In fact, I'm not sure, but I think they were inconsistent with it in much later seasons, switching between classic title cards and scenes. Correct me if I'm wrong.
The season 14 and 15 are consistant. However you may be watching a mix of both the international and the PBS version of the shows. In season 14 and 15 only the international broadcasters aired the true 1080 HD version of the series. The HD versions had the funky opening as well as scenes from the show in the bumpers. PBS aired the SD up-res vesion of the show with the classic bumpers.