I would say that generally 1st has three advantages, while 2nd has one:
1st:
1. First to establish quanta (Pillars, Towers, Novas, Immos etc.)
2. Your opponent draws a card and therefore starts with a full hand and may have to discard, you won't have to your first turn no matter what.
3. If the same amount of cards and no RT's, you win the deckout.
2nd:
1. You know what kind of deck your opponent is playing before you lay cards...usually.
The only other time I can think if first being a disadvantage is if you go first, play 3 pillars/towers and then your opponent goes next plays 3 stone towers and quicksands...but other than that, seems better to go first