Surprisingly enough (ich bin allein auf weiter Flur, scheint mir), I'm very happy with the Telekom. Their service is fine and the price is okay, so I've no reason for complaints. 1&1, on the other hand, seems to be pretty unreliable, so I wouldn't take that one.

If you get a large-ish van and it's a windy day, try to get someone else who can drive it. The stupid things react to wind quite viciously, so if you've no experience with them it'd be better to just let someone else take the wheel.