Never owned an Aegis, but I did own a Flash II and it was possibly my least favorite knife I've ever owned: poor ergos, cheap-feeling handle, loads of blade play, etc. So on the basis of that, I'd say the Aegis simply because it's not the Flash II.
Honestly, though, I wouldn't spend my money on either: there are lots of assisted opening offerings from other companies -- especially Kershaw -- that, at the same price points, are far higher quality, use better materials, and are backed up by better customer service.