Thats a personal question, imagine you are a charlover, and Someone ask you, what is better, mounts? Or outfits? Both are okey
In this case i prefer to buy set for a simple reason, its not Infinite, u always can boost more and boost more, while having set is limitated.
Then in my opinión is:
1) set full
2) 1 boost (30tc)
3) preys + 30tc boost
4) Preys + 2 boost
Thats only in the case u only wants yo Rush instead of wasting this money in other Game stuff.
Anyway this questions its depending how much money can u farm.
I hope i heped u,