I think the Giant Defy 1 offers great value for the money. You'll get years of use out of that bike. 105 are good quality components. Another model that is similar and should have similar price is the Felt Z85, if you can find one.
I would not worry about structural integrity of the top tube. Bikes are engineered to withstand some impact. I've fallen over on my bike a couple of times with no damage.
Head out to your local bike store and do some test rides. Personally, I much prefer a road bike with drop bars, but everyone is different.