I just started going all makeup crazy a little over a year ago when I needed good products for my besties wedding and MAC was the first place I went. I bought alot of products, but found out over the course of a few months that something they put in their formulation is horrible on ALOT of people's skin. Now I have $100 worth of beautiful blushes that I can't even use and were only used a few times. Unfortunately I depotted them so I can't return After that Sephora has become my home away from home. I follow alot of MAC artists on Instagram just to see all the makeup looks and have come to think that alot of the products are just hype. They make so much stuff Limited Edition just to keep it exclusive and have everyone buy right away and frankly I think it pisses more people off than makes happy. Also, I agree with everyone else about if you are jsut talking strictly Sephora Collection because I don't see a HUGE difference in packaging, they're both all black? But if talking all brands, when I want to feel luxurious and sophisticated, I'm whipping out my YSL lippies all the way baby! Ugh now I want to go use it right now hehe.
If you're wanting something similar to MAC, check out Inglot as well. I have so many of their products and are very comparable if not better and much cheaper. Swear by their loose powder for setting my makeup, pores no more! Single eyeshadows are only $6. You can find alot of dupe lists if you google. The YSM foundation is like $16, amazing but I'm not fond of the packaging of their foundations. Plus no parabens so I don't have to worry about breakouts.