The iPad is crippled, overpriced garbage. Why get a device that’s crippled by design when you can get a fully-functional, general purpose computer for the same price?
Surface is not a laptop replacement for coding. Try typing on one on a non-flat or moving surface. It sucks.
For $500, a Yogabook might be OK, but the Atom processor makes it horrid for anything beyond simple tasks. And the flat-plate keyboard stinks.