If you're like me, no matter what you buy now you'll wish you had gone with the other!! These are all good lenses. The lower apertures will be good in low light, but you're giving up the range of a zoom. If you go with the zoom, you'll end up with the f/4 or 2.8. I don't own any primes right now, and portraits and weddings is what I do for a living. The lenses I own have been very good to me. If I'm indoors, I use a flash, or turn on a few lights and shoot with the lowest aperture. There's a fashion photographer that shoots fora modelling agency and magazine adds. I don't know him, but he's a friend of a friends. He uses a Rebel with a 28 - 135 f/3.5-5.6? and his shots will blow you away. If I can find his name, I'll send you a link to his website. I don't know why he does this, but it comes down to working with what you have. I guess he's confident in his skill as a photograpgher, and his skill at CS2, I'm sure! I love my equipment, but I always want more.. ALWAYS! Buy what feels right. What are you going to school for?