ajaxbhoy1 , As you may surmise, whether taxi or Le Bus Direct somewhat depends on what "we" means.
Last September I arrived at CDG T2 and took a Taxi transfer to Gare Montparnasse. The cost was as mentioned above, 55 euros, and yes, some "hustlers" tried to get me into their taxis. The ride took about 45 minutes and the traffic was somewhat heavy at times. I believe the Taxi option is a fair deal if you are 1-2 passengers, for 3-4 it will be even better.
I hope your arrival is better than mine. For me, it was something of a nightmare. Take a look at my trip report if you want.
Sorry I was unclear. We're taking the train from CDG to Avignon and then returning to Paris and staying in Montparnasse. I've decided against using Le Bus Direct to get back to CDG because it's got too many bad reviews. I can deal with a delay getting into the city from the airport, but not on getting to the airport.
Best transfer will be the taxi cab. There are other options, which are simply not the best but may be less expensive.