So guys, I'll be spending a week in Ukraine, so I'm looking a good prepaid data service, ideally LTE but 3G would be good enough.
I'm not looking for a cheap solution but for a good one.

Also I have a 6 hours layover in Amsterdam and another 12 hours at Madrid so it would be great if I could use it there too..

I have my Tmobile international free roaming, but the services usually is not that good, so I rather prefer to spend money to get a better one.

Thanks in advance for the answers..

Ariel.