It all depends on how far you want to take the cross. Male selection is important, however I have found your best selections come from the offspring for parents. You will want to keep a mother of both the true parent mother, and one selected out of the offspring. You will also be selecting your male from the offspring as your parental stock if you want to take the strain further to stabilize it. F1's are seldom stable, and F2's is where the reccessive traits show.
Depending on where your JF seeds are from, their are at least 4 different lineages of parents for Juicy fruit all depending on where you acquired the seeds; a more common is the Early Durban X Fruity Thai, there is also a Durban/Afghani X Golden Triangle Thai land race, an Early Haze/Durban X Fruity Sativa(most likely of Thai decent), and there is one which resembles Sweet Tooth which has some Hawaiian Sativa in it's lineage. My personal belief is it is a special phenotype found in the old SSSC Durban Thai Highflier, then a Afghani male was crossed into this mother. Both of the BC versions I have seen resemble the Durban Thai highflier in characteristics.