Fishman Fluence Modern Alnico.
But I don't really have a favorite passive. Many come close, but most of them miss the mark by a little. I like the Air Norton distorted, but clean, it sounds too dark and round. I like the Duncan '59 clean, but distorted, it's all boom in the low notes and chirp in the high notes. I like the DiMarzio PAF 36th Anni, but I wished it wasn't as low output to match with hotter bridge pickups.
I find the problem often with passives is the ones that sound good clean don't sound as good distorted and viceversa. I also find that the ones that are a bit overwound to match with high output bridge pickups also tend to fatten and darken up too much for my taste. But I also hate neck pickups that are so underwound and low output that they're just plink plink plink scratch scratch scratch noises under tons of gain.