For what you're proposing, Route 128 is almost surely the best choice.
It's extremely simple to reach by car -- from 93, take Rt 128 (also called I-95) south to University Ave/Railroad Station exit (Exit 13) in Canton. The station is 1/4 mile from the exit, and there is plenty of parking.
Alternatively, you could go to South Station, which would be about 8-10 miles closer. However, South Station is in downtown Boston, which means that parking would be considerably more expensive and that the possibility of traffic delays would be greater.