Well, if we're only picking from decks we actually own, it's a pretty easy job - I own exactly five decks:
1/ Fey Tarot (Lo Scarabeo)
2/ Wildwood Tarot
3/ Tarot Illuminati
4/ PCS inna tin
5/ Morgan Greer Tarot
Not a bad selection, I think, but if I could choose from any possible decks (or at least, the ones I'm already hankering after...) I'd probably swap out the Fey for a Thoth (provided I could also bring a good guide to it). I might also go for the full-size version of the PCS Centennial deck rather than the tiny one in a tin, although I do find the tiny one a lot more comfortable to shuffle, and of course it's highly portable.
I was very disappointed with the Illuminati when I bought it (had LOVED several cards I'd seen online, was very tired and cranky and in Central London in a bookshop one evening and thought 'meh, why not?' then really didn't like a lot of the cards IRL) but I've revisited it this week and am enjoying it a lot more. Still, I'd be tempted to swap that out for the Mary El or the (first edition, I'm hearing disappointing things about quality of the... not sure if revised version is right but I think there's some changed cards so it's more than just a reprint?) Wild Unknown. Alternatively, if I was feeling more like a themed type deck I might go for the Norse or Green Witch. Possibly the Green Witch, as its slight fluffiness is perhaps a good counterbalance to the Thoth?
Next question, of course, is which book to bring...