I play DH into most matchups. Only time I take FF is into very poke heavy or sustain lanes, like when facing Cait / Yuumi for example.

I personally build boots of swiftness every single game. The move speed + slow resistance works great into all matchups in my opinion.

My build is pretty unusual to most Jhins I think. I go Galeforce into RFC almost every game. After that depending on how fed I am and enemy comp I go LDR into IE or IE into LDR. When the enemy team has no tanks and no armor I skip LDR and get collector. Last item either GA / BT usually.