Read a couple pages out of each. You'll know which you like.
Or just get them both. As a tip, I have found very little difference between Kaplan Essentials and the full volume Kaplan. They read almost word for word.
I used kaplan last year but didnt really like it that much. I just got the new Lange book, its called The Anesthesia Guide. I really like it, a lot of practical info. take a look if u guys get a chance.
The newest edition of hensley seems to be a easier read/interface than the previous. miller's chapters were a good intro before reading hensley as well. I bought Perrino TEE for the physics and specifics on valves.