Sad but true: nothing beats Sketchup for ease of use, flexibilty and price for 3d work. If sketchup was availab;e for linux, I would have delete my windows partition years ago.
Qcad? I use AUtocad daily and most CAD software use the same concept and shorcuts. You can invent a car that steers with your feet and uses handoperated brakes but no one will buy it. HenriFord and Benz a century ago decided the basic car control layout. Dont tell me about motorbikes ; you can't do half the things a car does with a bike. It's the same with some software like autocad which established itself as leader in the field.
All this to say I tried Qcad but dropped it because it wasn't possible at the time remap the keyboard shortcuts.
Now that googlesketchup is here, that's my package of choice for all around use. (I use autocad and SUpro at work).