Depends what “best option” means to you 
In my experience:
- 1st + 2nd year: SSBHV, mostly Sweetspot, Z2 was more like filler: yes, FTP grew over base phase but I could hold it only for 30-40min + couple times lost motivation, likely symptom of some kind of hormonal imbalance or overachieving. Still, felt strong and could hold Z3 very long time.
- 3rd year: Trad Base HV: not much FTP gains but training was very consistent. When reached to build phase, FTP increased quite quickly and I was actually able to hold it longer. Still not full hour, hoping to get there in coming season or even this year; due injury in summer, I’m currently again in build phase (no real need, just to complete full base/build cycle)