Clear offers no contract plans, so there is no two year commitment. They also offer a $35 a month but at a lower speed for or $50 for a higher speed connection (when available). Both unlimited data.

Though I don't believe they sell any dual mode (3G/4G) devices anymore, everything they do is only 4G now. They announced that change at the end of October. Supposedly the move was to make it less of a competitor to Sprint, it's largest wholesaler.