I think this depends largely on what kind of shot you’re trying to get.
If you quite like highly processed looking shots and you tend to shoot abstract or detail shots where composition and subject are the most important things, then I think you can get away with virtually any lens.
See the huge growth of iPhone photography for eg.
However, I’ve found that the majority of my shots are as wide an aperture as possible – it’s just what I prefer.
I also prefer my processing to look natural – no surreal HDR photos for me.
You don’t have to spend huge amounts though. I get by with just 2 fast lenses:
Tamron 17-50mm F2.8 (cost £250)
Canon 50mm F1.8 (cost £60)