Thanks @Raw e @doitsuyama for the answers.
I searched a bit before, and the answer were like yours: some say to go for zetas and others say to buy gear (and don't know why, but I was almost sure you guys would disaggre on that lol)
Well, a full set (of stun cuffs or syringes) would cost me 3 zetas. If I save 1400 ship currency a day (if I can keep getting rank 1) until I get to 82 and spend it all on zetas I'll get 20~25 zetas (already counting for a 2,5 zetas per week from the challenges), guess I can spend a bit on gear, because a zeta once I reach 82 seems like a sure thing. (But still don't know for which one I might go: Zaul or Zader? And what about the second? Zader? Zid? Well, I'll have 3 weeks to think lol)
Btw, for anybody that have some time to kill and want to make it easier to set your goals, I did this and it helps a lot:
Toon farming:

Gear farming: (the amount of gear I need to get them to the desired gear level from the gear level they already are)

(I'm just 250 syringes away from Rex, EP, Wiggs, Boba and STH G10. Easy job lol)