The best seasons are Hugtto, Go Princess, Suite, Heartcatch and Fresh. The best to start off with would be Heartcatch, it has a lot of the same staff that worked on Ojamajo Doremi (Umakoshi was the designer for both of them,you can really tell) These seasons to me have best pay-offs, best finales, least amount of episodes that feel like filler/fluff. Lot of other seasons I like but you can tell that had less passionate staff/more problems and a lot of them feel like they wasted a lot of potential (Either cause of staff or that the series is just made to sell little girl's toys so they gotta stick to that, can't go into too mature ideas or stray from the story plot/themes they are given)