I suggested Shadowmancer because that’s what I intend to take for my Kino build (Cryo/Kino3/Sorcerer2/Shadow2 full SPR), but I haven’t tested it yet, so maybe it’s bad !
But I can speak a bit for FF as I have a Wiz3/Ele3/FF3 : the strongest point of FF3 for me is single target/bossing. You have a combo which can do a lot of damage, but is limited to mostly one target without Linker !
Levitation + Enervation + Curse (Bone Pointing or Kurdaitcha, I prefer the first one personly) + Kundela Slash * 3 gives massive damage ! (but on cd longer than SM, so less useful for mobbing)
Blood Curse is fun to use, and can heal yourself and your group, but it can also kill you xD
Blood Bath/Blood Sucking means you don’t really need HP potion (but you’re gonna drink a lot of SP pots with the first combo)
And Levitation makes you immune to melee attacks, which is great in some area !
The main problem of FF3 with your build is the lack of Surespell (mostly for Blood Sucking), but you can try to replace it by some good CCs ! Other than that, I think FF3 is perfectly viable for your build, brings something different than SM (more single target, less SP consumption, longer CD), so at the end, it’s your choice depending on your playstyle