As you might guess, I've got both Midge Magic and Tying Small Flies and they're both really, really nice! Each has it's pluses.
As Flyman says, Engle's take on material, hooks and tactics is great and there's a ton of useful info in the text. The close up photography is quite good and very helpful in how it presents the tying techniques.
Of the two, I prefer the color photo studies in Midge Magic. It's also a treasure trove of valuable info. But if you want to know what really happens to a particular shade of thread or floss when it's submerged, and how closely that will then match the live subject you're trying to match... you can't beat midge magic!
I'm also quite partial to Ted Fauceglia's Mayflies. Aside from the stunning photography, the life cycle info is quite in depth and the author supplies photos of the handmade imitations of each of the stages of each of the respective mayfly's life cycle. So you get amazing photography, in depth entomology and accurate imitations, all in one "coffee table" presentation.
Having said all that (and knowing you as I do), if I were buying you a book and not a gift card, I'd get you Midge Magic.
"I've since learned to use the best knot rather than the one that uses the least line. I go through more tippet material but compensate by drinking cheaper whiskey. One must have priorities." ... Art Scheck