What's the best transportation to take between Vienna and Salzburg? I realize there are different train lines so wondering which one to take?
You might want to consider your location in Vienna. Some Westbahn trains stop at several S-Bahn stations in the city. The Blue route stops at Praterstern, Mitte, Renweg, Belvedere, Hauptbahnhof, Meidling. The Green route at Westbahnhof and Huetteldorf. You can also board the train and buy your ticket from the conductor. Spur of the moment, prices are good.
OEBB trains stop at Hauptbahnhof, Meidling, and the airport. Their prices are very good if you buy a Sparschiene Ticket, which is advance purchase nonrefundable. Spur of the moment can be expensive.
This is where local knowledge is helpful. From Dec. 15, Westbahn will only depart from Westbahnhof and Hütteldorf. Not really an issue, though, as both stations are easily accessed by the UBAHN.
Honestly, both Westbahn and ÖBB are excellent trains. Both get to Salzburg quickly. Westbahn has a different pricing system which allows you to buy more flexible tickets for not much money. Visit their website for more info. ÖBB offers a SparSchiene ticket for 19 euro but these much be purchased way ahead of time online as fares sell out and are tied to a specific train. Walk up fares on ÖBB are much more than walk up fares on Westbahn.
I would recommend the train from Wien WestBahnhof station to Salzburg Hbf. We took the Green line Westbahn and it is about a 2 1/2 hour ride. The website is westbahn.at
We took the Green line Westbahn
After December 15th there is no Green or Blue line anymore, just one Westbahn line. (Westbahn has accrued a net loss of about €140 million since starting its business, so they have to crank down their costs and services.)
Which train station you might use for departure to Salzburg depends from where in Vienna you start, i.e. which is reachable best.
Wien Hbf (main train station), metro U1, OeBB
Wien Meidling, metro U6, OeBB
Wien Westbahnhof, metro U3, Westbahn
Wien Hütteldorf, metro U4, Westbahn
I just did this trip this part Thursday and took the train. I used Westbhan and it was about a 2.5 hour train ride with beautiful scenery.