Is it better to go first or last in Vinci?
This is very difficult question to answer because so much of it depends on your experience, play-style, and how the random elements of the game turn out.  These games have sufficient complexity that, based on how they are played by humans, going either first or last might be an advantage.

It's certain that one's play-style preferences will affect this decision.  If you are one who more often likes to find a best response to your opponent's moves, then going later will be 'better' since it suits your play-style, this you'll win more often going later than going earlier.  However, if you're one who prefers to be more strategic, going earlier might yield you more wins.

Two things to note:


If you have the choice of consistently going in a certain order, keep choosing the one you have the most experience with.  This will enable you to remove one variable of the game, and allow you to improve your skill in the game faster.
There ARE certain combinations of races and powers that are clearly better, especially in terms of how they interact, than others.  This means that in certain games, it will be more advantageous to grab them, thus go earlier.  However, it's not at all clear that these situations happen often enough to offset any advantages (if they exist) from going later.