I love sketchbook pro by auto desk. It's a great program that can do pretty much anything you would ever need it to and works really well with the surface. I use it almost every day.
other programs that are great , Clip Studio Paint Pro (once known as Manga Studio 5 in the west) is your best bet, tons of tools, touch enabled interface, n-trig support, hdpi support and it makes even a Surface pro handle BIG files without a problem. If you download the program you can try all the features except for saving and they usually do sales every 3-4 months but the program itself is cheap priced to start with.
Medibang Paint is great too. Its basically a free clip studio paint .
I have the SurfaceBook 13.5" that I've been using for school, light gaming, and drawing casually on Ps - and I've found it to be enjoyable for the most part.
I also have a XP-Pen Screen Tablet Drawing for professionally . There are advantages to XP-Pen's offers (like the Artist 12 Pro) for professionals, and that is the digitizer itself. the pen is comfortable by drawing on the glossy screen directly .