Crit avoidance and offense primary (the last one on offense, CD, CC, health, maybe defense sets) are definitely worth keeping. Protection primary is situational but some tanks really benefit the most from a defense arrow with protection primary.
Health primary is mostly worth it on health and defense sets, defense primaries rarely ever get used.
If it's a speed set though, the only stats really worth keeping are protection and CA (if 15+). Anything else should be 20-25+ on a speed set to be worth using over a speed primary.
