Batman (Burton with Keaton and Nicholson) was an absolutely brilliant film, Nicholson was excellent as the Joker, and the dark tone of the film was very gripping.
Batman Returns (Burton with Keaton and Devito) was also a fantastic film, Devito as the Penguin especially was excellent. Overall the first two films, 4 1/2 stars.
Now, the second two films is a battle to see which is worst, Val Kilmer (Batman Forever) is by far the worst Batman I have ever seen. Though Tommy Lee Jones was quite good, the whole tone of the film was nothing like its predecessors, or the Nolan series (Batman Begins and The Dark Knight), which irreversibly damaged the film.
Batman & Robin, although without Val Kilmer, is the worst of the four. Pityful, and comedic acting, which has no real place in a Batman film ruined the experience. Overall for Batman Forever and Batman & Robin, 2 1/2 stars.
My advice would be to buy the first two (the Burton films) either together or seperately and completly do away with the final two (the Schumacher films).