Glad to hear Ilfochrome is still about...I was told it was out of production!
When I asked about colour printing supplies the question was why would you want to with today's scanners...
If you are just starting with transparencies, and only can afford to try one film go with Provia 100F, but give Velvia a try someday.
Provia's great. Some people say it ain't saturated, you just have to know how to use it ;-).
Velvia, IMO, is great for certain subjects only. Personally, I'm more of a "represent it as it really is" kinda guy, at least 90% of the time. The other 10%, I like to go hog-wild, so I use Velvia 50 :).
Astia is great too, great for skintones, especially in the studio, where you can control your contrast and lighting easier than in the field.
Negs are for people who don't know how to properly meter their shots ;). Just kiddin, I still shoot Portra, sometimes...
Astia 100F or provia 400x. My preferred choices, by far.