If I really had to make that choice on a pedal.... I'd go and buy the Line 6 X3, which has all in there what you'll ever need, and the sound quality is acceptable. I'd do that simply because on a one year tour, I'd probably like to play around with new sounds, and also use it as a practice preamp in hotel rooms and such.
Given the above (one year tour, only one pedal), I'd also immediately add the SansAmp RBI to my Rack -- so it's not anymore in the "pedals" category and still with me -- and have a good overdrive and D.I. option there. (Now if the RBI just was programmable as well...)
What else... ...maybe another very interesting idea would be:
Depending on how big an act you are, take along the MacBook Pro with NI GuitarRig for all your tone shaping need, and you also have a nice portable recording studio in case creativity suddendly rears its ugly head
For basses?! Don't know. That "one year on tour" idea is like damocles' sword hanging over my decision. On one hand, "if only one bass", it had to be the NAMM Anni, however, I'd hardly take that on tour for a year... it's too precious.
Maybe again, I'd go out and have a very loong look at a stealth Bongo HH and take that with me: Lots of possibilites to play around during that long long time... a cool looking bass, yet not a collectible.
hmmm.... Good point about the DI on the SansAmp, but I never cared for them with active basses - too much of a good thing, I guess. I'll stick with the Fulltone BassDrive as long as I get an 18v power source for it.