From personal experience, Wacom makes great tablet-computer hybrids for drawing, but unless you pay for the more expensive models (around $2,000), they're not very great on the computer part (4GB Ram, 64GB space, Intel 3 for the cheapest model). They can run Photoshop, and that's about it, but the pen drivers and screen are some of the best.
The SP4 is a bit better at being a computer, but the pen and interface are nowhere near as nice as Wacom's. Like KoB said, I'd put it as more for digital sketching on the go. Then again, some people draw exclusively on them, and it works out fine for them.
I have no experience with Android, or Apple devices for arting.
My recommendation: Surface Pro. Cheaper and seems more of a general-purpose machine that also does drawing. Also fewer cables to lug around, and can double as a decent computer for on-the-go computer needs.