Option 3 if you can swing it. They are guaranteeing you 2.5MBps (Million bits per second) with QOS (quality of Service). Where the others are "Up to" speeds. This means you should see a reliable connection and won't suffer from the delays that may happen durign high usage times.
QOS allows them to do traffic shaping and give priority to certain types of traffic or even whole IP ranges. This is how they are guaranteeing the 2.5Mbps.