I'm still thinking about it.

A united Middle Earth? I suppose the capital will have its own UN? Well, I for one do not believe Tolkien would have liked that idea. It is sufficient that each people is united in its own way. For the rest, let the King at Minas Tirith suffice.

Gandalf

The White city of Minas Anor (Minas Titrith) is beautiful and so on, but I have to say that by my opinion even for Ithilien the rebuild city of Osgiliath would be more propper capital.

Anyway. I voted for Rivendell. I confess my vote to be a bit given to my race, for I much desire the memory for the elves to remain in ME. And one good way would be to have the "Hometown of Elrond Halfelven" for a city, where the faith and future of the ME to be decided in council between the races, as in times of peril in the past.

Must perhaps put some clearance about the purpose of capital city: In eny union such town is not nesecarily the bigest, wealthiest or anyway dominant or supirior city. Unions have their regional head towns with local government (each from the listed ist most proper candidate in its area). The purpose of capital is to house the general council and other common structures of government, mostly related to setting the interactions between diferrent regions/states by synhronizing the basics of common low and organizing common army (if needed) and not even necessary to have rights on taxing and wealth policy (anyway some taxes to support the common union payments may occure).

I voted for Tharbad, because it's a bit of a mystery town, and the other choices were boring. Upon additional pondering, it kind of makes sense because it's between Arnor and Gondor, and Rohan is close by too. Besides, it needs to be rebuilt anyway so people don't keep losing their horses at the crossing. ...stupid Boromir, I bet that was a long walk.

I chose Tharbad as it is more centrally located and is away from the regional seats of power where the lobbyists make their homes. Making them travel will help the United Middle-earth government to be a little more free from their greedy mechanations. Had it not been for this, I would have chosen Osgiliath.

I didn't want Rivendell, Dale, or Michel Delving to lose their rustic character, which they would have, were they to become the capitol.

Tharbad is an abandoned town on the Greyflood about halfway between Gondor and Arnor. I believe it was abandoned because the river kept flooding and destroying it. I think it's mentioned only once in LotR when Boromir is describing his journey he says he lost in horse at the crossing at Tharbad (thus my earlier comment).

I am curious as to the reasoning behind the Dale-voters. Any of them care to explain?

Well those short lived characters were to be the lords of the Fourth Age and so I guess they didn't choose to pick an out of the way spot like Rivendell, just like they chose to bypass my flood prone river crossing of Tharbad. Were I a mean King, I would place it at Dol Amroth, which would preclude the legislators from going home for the weekend.