Why do you need a service? Just asking, but it seems like if you're mildly technically oriented and have control of the endpoint machines, then VLC or RDP is going to be cheap (free) and as good or better than any hosted application.
They're kind of 2 different approaches. If you own and control both endpoints, then VNC or RDP is likely the better way to go. If you're trying to connect to various end-point PCs that move around a lot and don't want to deal with firewall issues, then things like Go To My PC or copilot are going to be better, but the two approaches aren't really competitive, they solve different problems.
At any rate...this post isn't really getting me anywhere. :P Outside of copilot, nobody has even said a specific piece of software to use (except one for mac, which isn't terribly useful).