I assume Fullbring Shinigami Ichigo is extends to the middle of the Thousand Year Blood War (Before he get rekt by Yhwach).
IMO Fullbring Shinigami Ichigo is stronger.
Not only the fullbring enhanced his natural abilities to the point his sword swings was mistaken for getsuga tenshou, he also has combined reiatsu from gotei 13, then he proceed to destroy town sized pocket dimension by just activating his bankai, stops fully charged cero with his bare hand (Demonstrate the same thing when he catches Quilge's heilig pfeil with his hand and throws it back) and overwhelm Quilge even when he's in volstandig and absorbed Ayon.
So if there's a fight (somehow) between Vizard Arc Ichigo vs Fullbring Shinigami Ichigo then I believe FB Ichigo wins. Vizard Ichigo can power up further with hollow mask but I think it's pretty much similar to Quilge Opie's fight. And since his vasto lorde restricted then the only thing Vizard Ichigo has in here is hollow mask.
IMO, Volstandig Quilge is pretty much = Bankai Vizard Ichigo and Volstandig Quilge with Ayon Absorbed is pretty much = Bankai Vizard Ichigo with Hollow Mask.
And FB Ichigo still has Blut Vene should situation get out of hand. So yeah, voting for Fullbring Ichigo. Too bad we don't see much of this form tbh.
Also if we're doing chain of scaling stuff for lol it's gonna be like this:
Complete Fullbring Ichigo (This
one) is equal or even superior to Tsukishima (As he can cut off his hand and even overwhelm him at some point IIRC) who is equal to Post-Timeskip Byakuya who should technically stronger than his Pre-Timeskip form then it's gonna be:
Fullbring Bankai Ichigo > Fullbring Shikai Ichigo > Complete Fullbring Ichigo >= Tsukishima = Post-Timeskip Byakuya >= Pre-Timeskip Byakuya
Vizard Bankai Ichigo with Hollow Mask > Vizard Bankai Ichigo = Pre-Timeskip Byakuya
Though I'm not 100% sure with Vizard Ichigo scalling because his power is can be kinda inconsistent in this arc
and this scaling is just for lol anyway.