For me, it'd have to be a bog-standard early-60's-style strat.
I play around with all this other stuff and they're very nice and all (it would take a lot to part with my 335). But when it comes down to it, in my experience (how I play, etc) a strat can do a passable job of impersonating everything else to a greater or lesser degree... but I've always found that when you ain't got no strat, you really can't get that strat vibe going, you really miss it, and it's really depressing...
(Btw -I played a Variax for a couple of years, with the express idea of only having one guitar... I had no issues with the physical aspect of the thing - I actually loved the feel of it, but I could not get the strat model tweaked close enough to "strat" to satisfy my cravings. So my wife bought me a strat, I bought ITs, joined this forum, and ended up with LOADS of guitars!

)
If I'd started out differently many years ago, and didn't bond with "strat" early on (looks, sound, how it feels, etc) - then I'd probably be a PRS dude, like the one posted by Andrew W up the top...
But because of my inbuilt "strat-man" thing (and I haven't played one for over 6 months - it's all Gibbos and teles at the moment), I'd be a fool not to choose a strat.