You are facing exactly the same dilemma as I was when I started :lol:
I now have ITs, Apaches, and Sultans in three different strats. I've never got round to MMs. Only one guitar has had just the ITs, the others have had all of them.
The differences between the sets are actually quite small in a given guitar. They're definitely there, but not enough to say any one set is a wrong choice.
In my experience, with these three guitars:
The ITs sound good in all three but HEAVENLY in one of them (rosewood board, alder body). The Apaches made both guitars I tried them in sound fabulous (both alder, one with rosewood board, one maple neck). They've ended up in the rosewood board one because the maple neck guitar works equally well with Sultans or Apaches, and the rosewood board one feels "better" with Apaches.
If you lean towards a harder/grittier SRV sound, more like Rory Gallagher, ITs for definite. If you lean more towards the bubbly/mellow SRV sound, more like Jimi Hendrix (little wing, wind cries, etc), then I'd say Apaches.
They happily cover each other's territory - the IT neck for clean/semi-clean is gorgeous. The Apaches rock like good 'uns. (Purple Haze sounds best on Apaches in my house :lol:)
Btw, when I was in your position, I chose ITs for my first set (over MMs and Apaches in 3rd place) and I never looked back. A couple of years later I got some Apaches and was blown away by how good they are. They finally found their way into the guitar that the ITs were originally bought for. Either set would have suited me down to the ground in the first place.
Mother's Milks I've not tried, so I don't know for certain, but if you want a good early 60s woody strat tone, I believe that's the one. I wanted early 60s, but I wanted the ability to push the amp a bit more - so it was ITs for me. I have a gut feeling that it's ITs for you as well :D
Er... Nailbombs... that's kinda going in another direction there JP! :lol: