Rotom is actually one of my favorite Pokemon, especially from this generation. I always really liked Ghost type Pokemon and they're one of my favorite types. And idk. Rotom just really appealed to my tastes when it was revealed. I thought the typing was unique and the way you get him was very creative. Sure, it sucked having to wait til the right hours (I didn't even think about changing the DS clock so hush) and when you did, it was actually kind of scary! That music was really scary and I know it was for legendaries, but idk it worked for the little guy. That also caused a lot of controversy as to whether or not Rotom was considered a legendary Pokemon. :P
When the forms came out, I loved Rotom even more. I think they're great and just add even more to how unique the Pokemon is. My favorite form is Heat, but I think that's just because I love any Pokemon I can get a Fire move on. :P Wash is also really cute, so there's that. The Frost form is probably the best for irl though because let's be real, you could bring frozen food with you everywhere in your Rotom fridge and it would be pretty awesome.