Android is the best for portable. The hardware is extremely light with brilliant pressure sensitivity feel (Samsungs). I've done some testing lately and obviously the Wacom will be great as well but the Samsung's are great value as a sketchpad. I've also tested an iPad Air. Forget that as competitor. Sure, Apple has some cool apps including Procreate which has the best brush engine I have tested for awesome efficiency. The trouble is, the pen tech on iPads is utterly chronic and no way competes with Samsung. I've tested several pen types on the iPad and it's a disaster area compared to Wacom screens. So Krita Android would be king on portable Android devices if we had it. Of course there could be performance problems. I've been using Clover Paint and you can't do 4K res images like Procreate and still have smooth brushes at a large size but for a sketchpad, you wouldn't need that. Brush performance is useless if the pen tech is useless and Apple are not going to change that situation.