I love a good pair of athletic clothes. Seriously I won't even be working out, and their just comfy to wear. There's two popular brands of athletic clothes that are really similar, and I like things about both of them. Here's what I like and dislike about each brand.
Shorts: Lulu about $54-58. Many different styles and colors to choose from. They fit me pretty well. Only complaint is the weird holes in the speed short (far left). The other pair I have is without the built in undies. They are really comfortable but show pantie lines like crazy. Lucy typically $49-59. Again, many styles but not as many as Lulu. The one with the built in underwear is really comfy but has the ugly elastic things. Great to look for shorts on the sale rack (where I got mine, around $25). Overall Lulu get's my vote on this one.
Tops: Lulu mostly $48-58. Like their shorts, many styles and colors, especially in store. The straps can sometimes be uncomfortable and dig in my shoulders, but overall really cute and fun styles. Lucy $49-65. Even more styles and colors than Lulu, and typically more support. The darker blue you see in the bright blue Lucy top is a mesh back that allows a lot of air which I LOVE. Also has a decent sized pocket to hold a phone. Straps are pretty nice as well. Lucy wins this category.
Leggings: Lulu $82-92. Nice thick and stretchy fabric (Luon). A lot of different colors in the waistband. I found that I had to size up because the thighs were so tight but the waistband is now pretty loose, and its always falling down. Lucy $98-108. Not as many colors but a lot of different fits and styles. Favorite style is Perfect Core which has a higher waist. I discovered those, and will never buy from anywhere else. Similar fabric to Lulu, but I absolutely vote Lucy for this one.
My sports bras and my thin athletic jacket are from Lulu, so I can't really compare them but I'm a pretty big fan. The jacket is so versatile and I wear it everywhere. The sports bras are pretty nice with lots of support and fun colors to choose from. I also have an actual winter coat from Lulu that is practical for freezing winters, but also light enough that it's not cumbersome to carry around in school. It also has a cute fabric which is hard to explain, but I really like it. Lucy generally has really good sale items too, and I think mostly everything I have except the leggings are from the sale rack. I would check in store too if you want a good sale. But that's it! Hope you can get some use out of this!