You've laid out the traits I admire in each of them, we all do.
Rainbow Dash is funny sometimes, and also cool. She discovered that she liked to read books as well in Read it and Weep, one of my favourite episodes about her. She has her low points in the show as well like when she tried to force her pet Tortoise named Tank into not hibernating for the winter and blowing up the weather factory, and that other time she forced Fluttershy into a dangerous adventure to see dragons in Dragon Quest, but on the whole, I've seen more good than bad from Rainbow Dash. Her difficult moments are not an ongoing trend, sometimes when RD becomes snappy, she is in the right, like when she scolded her parents in Parental Glideance episode for reckless behavior and launching fireworks at her, I cannot fault her for that because she behaved like anybody else would in that situation, Rainbow Dash showed herself to be supportive of Fluttershy on numerous occasions as well, not just in Hurricane Fluttershy, but also in Flutter Brutter when Rainbow Dash became angry with Zephyr Breeze for taking advantage of Fluttershy's charity without giving back.
on Christmas I want to watch Best Gift Ever, but after Christmas I intend to give the series MLP FIM a rewatch starting from episode 1, I got the DVD collection, though some people may only watch it on Youtube or digital libraries, it's better if you can get the physical copy because you're not limited to your internet connection, bluray disc readers are affordable and they don't care how good your internet is or if you even have one at all.
As for your wish to be in Equestria because of the positivity that exists in that world, I know that feeling, it's such a beautiful world, I've seen it said by some other people they would wish for that, and now I understand why, what I'd give to end up in Equestria, none of my material possessions would mean anything in that situation. I don't know what type of Pony you'd wish to be in that fictional world, but I wish to be a Pegasus, in any case doing that would be more than just about flying, to agree to that would be a symbol, of appreciating their world and their culture. They're not perfect but they own up to it, embrace imperfection, and help each other through their problems. That is community spirit we do not always see in real life. Though admittedly, I see enough empathy on this forum. Nobody has ever once picked on us or accused us of anything negative for this wish.