Support Lineup

I see another one cursed person, huh. Let's see,
From my experience with Kintoki supports even using Mash, he gets killed easily I think he's best used as a backline with K scope and such to launch his NP the time he arrives. It also takes quite the support to keep him alive and such.
Vlad is weak without arts teams, so the only people using him are people who have Tamamo, and A great arts tanker.
Nightingale is nice and is a buster support, but Merlin is coming, so yeah.
It's either Kintoki or Vlad, so it's Vlad for me due to higher NP making people want them for the great offense than Kintoki, but if that doesn't work go with Kintoki with K scope is what I'm thinking.

None of them are great for support but Vlad should get you the most FP. Speaking from experience kintoki gives no friend points ever.

I will say it depends a little on the CEs you have.
If you have any CE with 50% NP and got Kintoki's second skill to Lv. 10, he can be very useful to your friends for daily quest. But that kind of depends on whether your friends farm a lot and if they have good ST servant.
Otherwise, Vlad is probably better.
Nightingale could be useful with high difficulty, but she will be better after her strengthening quest.

Typically people use the berserker slot for farming. The one exception might be herc but it's rare. If you have even a 3 star kiyo leveled up you could put it there. Otherwise just put the Vlad and expect it to be used occasionally only.

There are better alternatives to the roles performed by Kintoki and Nightingale (ST DPS and Support respectively), but Vlad is near irreplaceable as an Arts Berserker/DPS.

So Vlad is better for support. Him being at NP 4 is also really good. Be sure to put fitting CEs though, generally Arts boosters like Formalcraft of Projection.