Thuja

I think it would have to depend on the fabric being used. A pegasi who flys around a lot might not like something that's too heavy or bulky. Like wool or something? While a pegasi might enjoy something like Rayon or tulle, something that flows nicely. Maybe a knit with a lot of stretch to it to make it a bit more comfortable along the back especially if they fly a lot. I'd like to think that most pegasi who like to wear some sort of clothing prefer something light instead of a denser fabric like denim or, again, wool. I'm sure it's rather exhilarating to fly and feel the air brush through the fur... Or whatever type of hair/ fur ponies may have in world... So they'd want some that flows nicely and is breathable. They could also prefer a linen suit over a silk for more breath-ability, or have a linen suit to wear as an everyday thing while the silk is only for specific events? As for putting clothing on, could be a possibility that they have devices that you can latch onto a piece of clothing to hold onto it while you put it on, like one of those things that helps you put on a bracelet with one hand? They can twist their head around a far ways from what I've seen of ponies reaching back to take something out of a pack or whatever so I wouldn't doubt that they can hold something in their mouths as they tried putting their wings through a jacket hole. There could be different cuts of clothing that'll be easier to put on with wings on your back, almost like princess seams but they curve along your back to fit better with wings????????? Idk, interesting thing to think about though!!