I guess I'm very careful with my phones.... My phone has become a fashion accessory I guess you could say. I change cases with my outfits and consequently have a huge case collection. (Moving from the S3 to the S4 hurt a little). I buy all of my cases from amazon.com for at the most, 5 bux, usually around a dollar. I don't care for bulk or for cases which detract from the lines of the phone and as I said earlier, I guess I'm careful.
I can't say that I've not dropped my phone, because I have, but I've never broken a phone or scratched a screen. No, I don't keep my phone in my purse at all - I can't hear it ring in there despite the claim that the volume is amplified in some way when the phone is in a pocket or purse, so I keep it in my hand 90% of the time.
I say all that to say, that for my use of the phone, cheapy cases have served me quite well over the years.