FP4 is one of my favourites; probably my favourite. It has really pleasing qualities. I wish there were more films that would behave like it does. I used to use a lot of PanF, but I find it's speed really slows me down a lot of the time. PanF has less grain, we all know that, so if you're looking for absolutely less grain, then it's better than FP4 for sure. However, I find the grain in FP4 to be even more pleasing than PanF. I used to think I preferred less grain, and that's why PanF was my go to slow film for a while, and I do still use it for those times I want practically no grain. Now, FP4 has filled in the space of: decent speed for many situations, great tonality and curves (better than PanF) and wonderful grain structure. Also, I really don't think it lacks 'pop' at all, perhaps it's your subject matter and exposure that's throwing you off? I find the contrast to be very nice. The pop you're referring to with PanF is probably the quick shadow cut-off, which can be tough to print if not exposed properly. I find FP4 very forgiving and a beauty to print. it's quite a difference in terms of amount of grain compared to HP5 and Tri-x. What's your development procedure?
Btw, I totally understand if it seems that a film just doesn't work for you. I've been there with a few films, but it's mostly due to my heavy interest in grain structure. But if you do like the traditional grain structure of FP4, I would definitely say keep trying it and you will probably learn to love it. You're right about other similar speed emulsions having finer grain. It's definitely not the best choice for least amount of grain. Try Neopan 100, Tmax 100, or Delta 100 instead, if that's the case.