I think you need to consider the context here. What sort of wedding is it?
- Day or evening? (Black may be more appropriate for an evening affair)
- Indoor or outdoor? (No stilettos if you're going to be walking on grass!)
- Does the couple like colour (& would therefore frown at black?)
- Will the bride wear white (& therefore not be OK with the white in dress #2)?
In my culture, it's not appropriate to wear solid black to a wedding, so I don't know if my opinion counts much for dress #3, but personally I would push up the sleeves & add a colourful scarf or necklace to break up the expanse of black a little (you could also swap out the belt for a colourful one, but then that would look more casual & like a real coat).
Personally I like dress #1 the most for its versatility - it would look good with a cream/ white/ brown scarf (& gold jewellery) for a more casual or day affair, but also black or navy for an evening affair. The silhouette also makes it more versatile for other situations too (you could easily layer another skirt or a cropped shirt over the top of the dress, to get more mileage out of it after the wedding as separates. It also wouldn't look out of place with tights). This will depend on your figure & lifestyle needs of course, though.
The last point is the shoes. Stilettos may not be appropriate for your everyday needs, but have you considered other events too? Would you find the Mary Janes to be more appropriate for a job interview, for example? Or a funeral? Or even another wedding? They look more like ankle wrap block heels to me personally than Mary Janes, so I think they are expecting bit more versatile but still more casual than the stilettos. You know your lifestyle needs though, so only you can decide this, but I just thought I'd throw something else out there in terms of appropriacy.
Don't sacrifice your comfort if you think the stilettos or dress #1 would be too much for you, though - I'm sure the couple care more about you being there for them on their special day, as opposed to whether you wore strappy heels or stilettos!