While I have not personally "Done" any of the tours; I am VERY familiar with them. It really just depends on what is most important to you and what you want to do during your tour.
Behind the Scenes; as stated you get to touch a penguin and a shark and see a lot of the backstage areas that every day guests do not get to see.
Sealion UP Close: You get a photo (no touching as far as I know) with a sealion that is in the SeaLion High Show; and then get a bucket of fish to feed out to the seals/sealions at Pacific Point Preserve. So there really isn't a whole lot of "interaction" but you get to do more than the average guest when it comes to sealions. You can bring your camera, I believe.
Dolphin UpClose: Takes place 100% at Dolphin Cove. There are some trainers that are there for the Dolphin Encounter Guests, and some for the Tour. Basically, during each tour you will get to "step up" to the dolphins 3 times for about 5 minutes each time, with 5 minute breaks inbetween. The Encounter Guests only get one step up; and the 5 minutes in between is to switch out the encounter guests, if that makes any sense. No idea on policies with photos.
Wild Arctic Up Close Tour: In my opinion when it comes to actual hands on, animal interaction time; this is the best tour; and the one you get the most time with animals. You do have to put all of your personal items (cameras included) in a locker at the beginning of the tour; but there are photographers there taking your photo of all interactions. YOu get a talk about the food prep area of wild arctic, then (generally speaking, sometimes animals decide they don't want to do a tour and this can change from day to day) you get to meet, touch and get a photo with seals, beluga whales, and walrus. The walrus you will NOT get to touch, but will get a photo and a chance to feed. It's posted I think as an hour tour, but generally (especially if its a full tour) will run a little longer than that.
And I lied, I am really not all that familiar with the Penguin Up Close tour.....I don't know anything about it, except that it meets by the Pacific Point Feeder Booth. Sorry!
Hopefully this helps you a little bit.