Paris train departures - which airport?

Both the major airports in Paris are well out of town and there isn't a huge difference in ease of travel to central rail stations. Strasbourg is Gare de l'Est, so whether you fly in to CDG or Orly your quickest route will be to get the RER line B to Gare du Nord and walk or take the metro to Gare de l'Est (Nord and Est are in easy walking distance unless you have very heavy luggage or have mobility problems). I would think that issues of price/comfort for your flight would hugely outweigh any difference in airport travel.

It's a hairsplitter. You have to go into town in both cases since the trains leave from Gare de l'Est. Roissy would probably win on metro/rer time, but you have to figure in such stupid things as the number of steps from the airplane door to the train platform, how many customs agents are on duty, etc. Hopping on the commuter system to hopping off is a bit less than an hour in either case, maybe right at an hour.

Once at the airport why not stay there and take a plane to Strasbourg? By the time you get into Paris, and to the train, it would be quicker and probably cheap if you tacked on to you original ticket.

Thank you, that is all most helpful.

As others have said, find the best airfare deal you can with a schedule that you like and fly into whichever airport is served by the airline that offers it. However, if you fly into CDG and your flight arrives at the right time, you won't have to go into Paris. Direct TGVs from CDG to Strasbourg depart at 07:28 and 12:28. You also can take a TGV departing at 09:58 for a 9-minute ride from CDG to Marne la Vallee-Chessy, wait 25 minutes, and connect there to a TGV to Strasbourg.