Ah, so a winner for a winter wedding! I have not voted, as I'm afraid that I don't think any of the three is quite right ... sorry!
From your previous post about the Reiss trousers (& hopefully matching jacket too!), you seem to like a minimal, slightly masculine aesthetic?
- The green dress is fine, & could look good with the right accessories - but the matte fabric combined with the dark shade make it look a bit flat.
- The navy & cream dress is a smart office dress. Plus, even though it's a winter wedding I presume there'll be heating! Bouclé looks hot & itchy & sweaty ...
- The suit combined with the blouse & cravat is lovely. But the suit is a brown tweedy-looking one &, despite the great cut, is very much daytime IMO.
A winter wedding somewhere fancy will, I'm sure, make full use of the shorter days & cooler temperatures & (especially by evening time) have fires lit & candles flickering. It therefore seems like a bit of a missed opportunity to go for fabrics that have no light-reflecting qualities like the green dress (in fact all of your choices). Velvet, silk, satin, metallic jacquard & the like would be my choice. They can shine in a low-key way - something like a matte satin would still have a soft lustre to it.
I think the idea of a trouser suit is great. And it sounds more like your style. I really like the Me+Em ones (which you can still buy if you're a size 4!), & the Serena Bute & NRBY ones. And I think the blouse & cravat styling that you were thinking of would work splendidly - it would look really elegant. Both the Me+Em ones in the photos are worn with tops (one satin, one silk pussy bow) that would work.
What I would say though, is that cotton velvet is more hard-wearing & less prone to flattening of the pile than viscose-silk velvet - that can be a real issue with trousers, especially on the bum!