While I don't have the set-up, a lot of my friends have both ipad pro and apple pencil and they love it (consequentially, I went with a cintiq 13HD myself with is 800USD). You just have to consider the use you'll get out of it:
One of my friends (who has an pro and pencil) said it would be better to have a cintiq because I wouldn't have to constantly worry about updates, including app updates and incompatibility. The biggest downside for me though is, unless you have a station to permanently set it up with, and you don't intend on moving it much, is the constant set up. I have to unplug and replug every time I use it. Outside of that, though, I really enjoy working on it — MUCH better than a regular bamboo/intuos.
That being said, If you are more of a portable person, I'd definitely get a pro and pencil (At least the 10-inch if you're on a budget). Procreate, autodesk sketchbook, and Affinity Designer and Photo are some good apps for it (Affinity is especially a nice alternative to Adobe photoshop and Illustrator). I wouldn't trade my cinitq for one, but I'd surely add it to my arsenal of tools! You can also turn it into a display for your computer, though admittedly, I don't know how well that works.