I'm personally set on the companion because it does both. I expect any tablet I get to be outdated soon enough, but my desktop will always be good. I'll only use it on the go for sketching anyway.
I'd be wary about getting a Surface Pro 3. I've owned one twice, got rid of it twice. It's a fine piece of hardware, but it's not really suited for artistic software outside of just sketching. It all boils down to not having any hotkeys to do anything. This is why I recommended the Cintiq Companion. It's true you can get a…