I'm surprised no one has mentioned
Astrill. It's only $5.50/month if you go with the 12 month plan, has servers in 44 countries, and you can do instant switching between countries on demand.
But the part I like best: it's FAST. No slowdown whatsoever. And I never have any trouble connecting.
Hope that doesn't make me sound like a company shill, since I've got no affiliation with them. But after having been through over half a dozen commercial vpns, this one has worked best for me.
btw: my second choice is ProXPN. Which I'm also surprised no one has mentioned.