I shot with the 550D since March, sold it this week with the 18-55 and got the 60D body only. I also have a canon 24mm f2.8 with a Century x.7 wide adapter, Canon 50mm f1.8 and a 55-250 iS zoom. All very sharp, but I need the wide range back that I had with the 18-55.
I'm getting the Tamron 17-50 f2.8. It's sharp and a fast zoom. There just aren't that many choices in that zoom and price range that can beat it, or should I say none.
I wouldn't recommend the 55-250 for a primary lens unless you plan to use a tripod or other support although it's another Canon bargain lens for $220.
If you have access to Ebay, why not buy used lenses. People buy then and sell them after one use and upgrade. You can get the 18-55 kit lens for $50 bucks to see what works for you then sell it in 6 months and get your $50 bucks back.