For what you're asking, I'd say Stormy. To my ears it's more "open" sounding (more clarity) than the Mule neck and would better suit a tele bridge pup. In fact, it might even sound clearer than the Texas Special in the bridge! (from my experience/memory of that pickup).
However, do think about another option:
You love the middle position sound at the moment - I'd be so scared of losing that (if I replaced the neck single with a humbucker).
When I was first sorting out various teles with pickups a few years back, I found that middle tone is VERY fragile when it comes to swapping pickups (and adjusting their height). The sound you love can disappear VERY quickly and you struggle to get it back - it's a careful balance between bridge and neck pickup. Years ago I gigged with an SH tele - I had to use the middle as my "bridge" tone (it wasn't a tele middle sound at all), because with the amp adjusted for using the humbucker, the bridge on its own was unusable. I'd been expecting a highly versatile instrument when I put the humbucker in. But it turned into much more of a one-trick-pony.
So I'd strongly suggest that you consider getting a BKP tele set and a four-way switch. I replaced both a Texas Special set and the set that was on a Baja (twisted tele and something, forgotten) with the original BKP Blackguard Flat 50s. That set is now called... er... help me out someone(!) ... I think it's the Flat 52 set?
For me, that set blew both stock sets out of the water with their own tone - the guitars didn't sound much different but LOADS better, almost like it was what the original pups were doing but with more authority (the tele with Texas Specials opened up in the clarity, the other got more robust with no loss of its clarity and tele sparkle). After a bit of height adjustment between bridge and neck, I had the middle sound back where I wanted it.
The addition of a four-way (adds a "bridge and neck in series" option to the standard configuration) gives you a "humbucker" tone. With this BKP set it's VERY usable. I find with my Yardbirds set that the "both in series" position doesn't really bring anything to the party (partly because the neck is so good on its own). But the Blackguard set, wow, it's Les Paul time without changing guitar (or amp settings - it all balances nicely).
I know what you're thinking - but I love my Texas Special bridge! Trust me, you will ADORE the Blackguard bridge. Also, look at it this way - a tele set is £140, a single humbucker is £117... not much different... plus you won't have to hack up the scratch-plate and dig a bigger hole in the guitar (or is yours already routed for a humbucker?).
