Hello @blessingscaptured! I was in your shoes about two years ago. I ended up spending my graduation money on a used Canon 17-55mm 2.8 IS for my Canon 60D (crop sensor).
Wow let me tell you that it has been the one of the best photography investments I have ever made. It has a fixed 2.8 aperture all the way through… and it is AWESOME. I find it especially good for weddings or candid photos where you often have to set your aperture and then forget about it as you constantly change focal lengths!
Also, as you get to the long end of the lens, bokeh (background blur) really starts to play in very nicely.
On your alternative choice (the 17-70) I thought I would want a longer focal length too when I was going to purchase this lens and seriously considered the Tamron 24-70mm as an alternative (it’s still on my wish list).
However, on my crop sensor I found I often am wanting the wide angle as opposed to the long angle. In my situations, I can more often take a step forward, or even crop in in a serious pinch, then take a step back—like when my back is against a wall.
When I want reach, I want to say I want a bit more than 70mm and I pull out my 18-200mm; this is why I shoot with two bodies during weddings when I don’t have time to swap lenses.
If you get the chance to shoot with two bodies (say, one with the 17-50 and one with the 70-300), the gap between 50mm and 70mm isn’t too much to be noticeable, at least in my experience shooting two bodies with a 17-55 and a 70-200.
Long story short… if I were you, I’d go with the 17-50 2.8.
Hope this helps! Tag @loganlamar if you have more questions 🙂