Mhh you're partly rights, not all of Bach p&f are interesting, I got well from book I with the first two and 14 in F#m, I don't mind 23 in B major. From book II I studied n.12 and 18.
Well about the easiest I would say the first from book I also the fugue it's pretty fluent when you study. But most of about WTC depends on the reason why you have to play it...
I mean why do you have to play WTC? does your teacher asked you to do or you feel that it must be a step you have to take as pianist? for me worked the second one, after I've studied a couple of them my skills got better and a lot. Bach for pianists it's like a kinda gym, then Beethoven would be much more easier to approach more than you could think
