Well in the UK I tend to vote where I think my rights as a gay person are most protected.
It is on the record that over 50% of Conservatives did not want the Civil Partnership, and believe it should be repealed. There are a large number among the part who feel that homosexuality should be recriminalised. - Very unlikely to get my vote!
I personally feel that under the premiership of Tony Blair the labour party has brought about some of the most significant advances in the protection of gays and as such makes the UK one of the better places to be gay under the law. I will continue to vote for labour until I think that there is a change in the tide.