I'm staying in Lans for 2 nights.....then dropping off my rental car and taking a train to Vienna. What train would be the fastest and most comfortable?
Railjet, OEBB's long distance brand, has direct trains.
There is a train every hour, they all take the same time (~4 hours 15 minutes) and are all identical, just pick whichever departure time suits you.
For info, etc., see here (scroll down for Innsbruck): https://www.seat61.com/international-trains/trains-from-Vienna.htm