i have all 3 books.
the answer to your question is dependant upon what you plan to use the books for.
personally, i think trying to read the huge tintinalli cover to cover is ridiculous and a poor allocation of study time. but, if you are treating a patient and want to learn more...or even better, you treated an interesting patient and want to read more at home afterwards to reinforce it, then the big book is the way to be.
if you want a book to have on hand with you in the department, the smaller version of tintinalli is good. naturally, its less informative than the big one, which is why its smaller. but, i think it does the trick.
just the facts is nice because its a rapid review. better for later in residency when you're reviewing for boards. to use it as a primary academic text to learn from during resideny is a bad move. this book does have a supplemental book that's 700 review questions. in my opinion, the questions are way too easy when compared to Peer VII, CORD, etc. and are not the best way to prepare for in service or boards.
just the facts also has a peds version. i own it but i've never cracked it after i realized i couldn't use main "just the facts" as a primary reading source.