I have joined the fandom at the end of Season 1. I was constantly seeing pony fans spamming about how great the show is all over youtube and just decided to watch it because "Why not, I have nothing else to do, might as well check it out". I watched the entire Season 1 in 2 days before I even realized it :D . After that I kinda forgot about it till somewhere mid Season 4 and watching all the episodes I missed got me hooked. Quality has definitely improved a lot since the first season.
Favorite ponies would be RD, Luna, and Twilight. Though I also really love Discord :D
And Ultra Fast Pony is basically just like any other abridged series. A parody that pokes fun at the show that somehow ends up being really entertaining to watch xD
Chrysalis: No, it must be pure love!
Twilight: And you came looking for it in Equestria?
Chrysalis: Yes.
Twilight: That's stupid. You're stupid!