Favorite- fma/fmab (they both have qualities I like and I kinda lump them in together in my mind anyways)
Least favorite- I dislike most isekai premises, and the amount of fanservice it seems to put in is really repulsive, from what I've seen. The only isekai I've seen is Sao, and that wasn't really a point for the isekai genre in my mind. Really bland and uninteresting, and completely ruined the best character in a mere few episodes.