My favorites have always been the glittery g1 ponies (Sparkle ponies) and the longer looking ponies (the sweetheart ponies I think?). I have a few baby glitter ponies that are pretty awesome. My cousins when they were little also had a TON of Mlp ponies (which sadly they are gone now *sigh*!). I had a love for the Christmas pony "Merry Treat" that my cousins had. I finally bought her a couple of months ago cause I always wanted her as a kid!!
I found a lot of "petite ponies" in my toys but sadly a lot of them have their tails cut (I guess my mom didn't want them tangled!) I took pictures of them and donated them to the My Little Wiki.
In the future I'll probably collect the rest of the glitter ponies. I also have the mlp castle and the sparkly baby carriage thing which I may sell in the future (I'm missing some of the pieces though)
All in all, it has been super fun doing research about the ponies. I hope to ask you all questions pretty soon about the value of some things.
Thanks so much for the warm greetings!!!