Sorry, can't recommend a hub because I've never had the problem. But here's my thoughts anyhow...

USB hubs are pretty stupid devices so your issue really boils down to "how much power do you need". Choice of new hub is then down to brand perception /reputation / reliability and size of power supply!

I've just had a Wiki at the USB spec and it suggests that each powered port should be able to provide up to 500ma.

External USB powered hard discs are usually the biggest drain; a lot of them hook up to your pc/hub using 2 usb "A" connectors because that's the only way they can grab enough power from the USB system without exceeding the 500ma per port limit.

So, what devices are hooked up, whats the total drain and does this exceed your wall wart output? If this is the case the simple answer might be just to get a higher
capacity wall wart.

Alternatively, as most PCs provide power to all USB ports available, perhaps you could shuffle things around a bit? Hang the high drain stuff directly off the ports on your PC and hang the low drain stuff (such as printer, scanner, USB stick, webcam) off the hub.

Hope this helps!

John