I have always liked some of the less popular ones. I like the ninety series jets, which are all but forgotten. They represent an important transition era and designers learned a great deal from the early jet fighters.
I like the English Electric Lightnings, their vertical engine configuration always intrigued me and the more I learned about their design, but more it appealed to me.
I like the F-101 Voodoos. Not that they were particularly good, nor had a long service life, I just liked the design from the era.
I like the R/A-5 Vigilantes. Such a sleek design, reduced to reconnaissance roles. My father's childhood best friend flew them in Vietnam and was lost on mission. Some of his possessions ended up with my dad afterwards. Years later, when I went off to boarding school, my dad gave me his friend's portable chess set, still inscribed with his friends name. Him holding onto that chess set for thirty years made me think, long and hard, about a lot of things. Maybe someday I'll pass it on to my kid and explain where it came from.
The list goes on. There's too many interesting designs out there to decide upon one or five.