Fair enough Klev. I just think it's personal preference. I've heard the argument that the bigger the screen the bigger the tablet size should be, and it sounds reasonable enough in theory that I could see it swaying 1st time users, but it's never held water for me.
As a freelancer, I often have to take what's given to me, and sometimes I get a large tablet and a relatively small screen (24") and it's uncomfortable for me, as my preference is a medium tablet and a bigger screen. I guess it's somewhat like mouse tracking speed, everyone in a while I need to slow mine down, but for the vast majority of time I like it north of the mid point. A slow mouse just kills me.
My only advice to new buyers is to buy from a place where you can return to. And with the small tablets running about 1/2 the cost of large ones, it might be better to start small and see if bigger is needed.