I have yet to find a single carry-on bag that carries all the vital stuff I need and that will fit all of the various and changing airline carry on size restrictions. I find I have to have several bags in varying sizes for different sets of rules.

On my last trip to Europe, due to the final failure of my favorite carry on bag just before the flight, I ended up using a standard gym type bag like this:
http://www.amazon.com/Nike-Brasilia-Medi...gym+bag+for+men

And it worked so well, it is now my go to choice.
Good points:
1) relatively cheap (cheaper than "dedicated" luggage).
2) light
3) shoulder strap (removable)
4) various sizes available to meet airline regs.
5) dual zippers that meet to close bag allow a small lock to keep prying hands out.
6) no internal or hard frame, so its "stuffable" and can conform better to odd space left in the overhead compartment.

I also have one of the traditional style folding garment bags, but don't use it anymore as its to big to meet any of the carry on regulations on the airlines that I use.

On a slightly different topic, during my trip I noticed that laptops and pads got a lot of attention from the TSA, who ignored smartphones and 7" style tablets. . .both of which I carried and went through the checkpoints and x-ray without a second glance.