PS: I'm in Spain and this connection is costing me about 40€ with free phone calls.
The best way to use it - set-up your personal cloud. Or create a tor exit node / relay. Or host a linux repository mirror. Endless possibilities actually.
If using over WiFi the only downside is that in order to use all this speed you have to use ac capable router and of course - devices. I'd buy a router if I'd have devices which would utilise ac standard.
Although you can always use wired..
Self-hosting owncloud behind a dedicated firewall (openbsd router, or carambola running freebsd+pf or openwrt) is a very good use case.
> tor exit node / relay.
That's an AWFUL and very STUPID idea and should be avoided!!! Unless you're a lawyer who understands what the repercussions are, it's a really-really-realy AWFUL idea. In case someone attacks something using your exit node, the police will, the judge and everyone in between will have a very hard time understanding why would you chose to run an exit node from your place. SO when shit hits the fun you'll need to explain (and convince) non-technical people about a choice which seems obviously absurd. Note that the police will come and your place, seize everything that looks like an electronic device, retain all this material for as long as their investigation goes on and only in the end you MIGHT be able to get your things back. Why should you risk something like that? If you IP is listed as exit node, you'll be banned from some websites, creating another set of problems. If you want to run a relay, sure you can do it. If it's a listed relay might again be blocked from accessing some web content, but mind you that relays these days are getting faster and faster and even though your connection is fast, it might actually make the Tor network slower, hence I don't think that's a good idea either.