I would say 4 is my favourite, but obviously I have a fairly large bias towards it considering the number of times I played it and that it was one of the first really great RPGs I ever played; it was between this and Phantasy Star 2.
The one thing 3 had over 4 (from my childhood memories) was that 3 had way more monster arena stuff that I liked. That was a major thing back in the day.
I describe myself as a little dose of toxic masculinity.