I disagree about there being nothing to like about Rainbow Dash.
• She stood up for Fluttershy in The Cutie Mark Chronicles (the sonic rainboom she performed was later revealed to be the cause of the rest of the mane 6 getting their cutie marks)
• She saved Rarity's life in Sonic Rainboom.
• Just like Fluttershy's squeaks, some people find it cute when Rainbow Dash's voice cracks.
• She is arrogant and competitive, but she's also ambitious which is a good quality to have.
• Selfish...meh. Personally, I think Rarity is the most selfish of the mane 6, but to each their own.
See this thread if you'd like to know what else there is to like about Rainbow Dash.
You don't have to like RD (and i'm not really trying to debate, just bringing up a few reasons that I think justify liking Rainbow Dash), but there are definitely legitimate reasons to like her and the rest of the mane 6.
Well...