We found using a car service was the very best way to go. We used Shuttle Inter. The driver was standing outside customs with a sign for us. His car was parked right at the curb- no standing in line for a taxi and he helped us out with our luggage. Price for up to 1-3 people is EUR 55. There were 3 of us and I advised them we had a lot of luggage - no problem- they had a minivan at the same price. We used them on the return from the PHV at the same price. Driver was there right on time. I prefer a fixed, reasonable price. Traffic in Paris, at times, can be unpredictable, horrific and a taxi meter can run up very quickly. We really liked this particular service- the drivers spoke perfect English, were friendly, and when congestion was encountered on the way back to CDG (at 2 pm) he took an alternate route, which a taxi might not do.

Roissybus is cheaper and practical so long as you realize it's basically a city bus with some additional storage for baggage in the passenger area; it does not have a baggage area under the bus nor anyone to help you. Also keep in mind it has a fixed route so if there is traffic congestion it's unlikely that the driver will deviate. Also keep in mind that if it's raining, the walk to/from the hotel is a good 10 minutes with no cover.