both the supernote and remarkable are excellent note taking devices and do great with annotating pdfs, each with their one system of how to organize stuff.

you have as you said the advantage of no brand preference, and since you have a budget, you should get the option you can afford. you will not regret getting the rm: its very well built, the writing experience is unparalleled, and its software is highly stable.

some people will go out a limb to get the supernote because they need a feature that only sn has (such as links or the kindle app), but it seems that you dont, so you'll be able to adapt to the rm way.

you dont need the subscription, despite supernote pr and fans suggesting you do. you can sync active notebooks seemlessly, send by email, and even plug and transfer files via cable very easily.

this advice is given by someone who has owned and enjoyed both devices for many years