I know there are multiple websites for buying train tickets in Europe. Any advice as to which site is best for TGV tickets? Thank you.
it is always wise to buy from the people who actually run the trains. SNCF in this case. https://www.sncf.com/fr
The SNCF ticket selling website is actually www.sncf-connect.com
The other website above is corporate + train times only. Confusing? Yes. Welcome to France.
SNCF also have a cheaper version of the TGV - doing the same speeds. It is called OUIGO.
https://www.sncf-connect.com/en-en/ouigo
The cheaper train gets you there in the same amount of time but has no amenities except a toilet, crowded seating, 3across and 1 single seat, and more limited luggage storage-- but the price can be interesting.
No judgement, just pros and cons.
And using the app seems easy also.
Over the years, SNCF has compulsively fiddled with its website and become increasingly annoying. The current link, for instance, can't decide whether to consistently serve a foreign guest in French or English. The option is to use the Trainline site, paying a small fee for a smoother experience.
southam makes a good point -- I too have found the sncf website to be increasingly hard to use and occasionally use Trainline which is easy to use.
And Bets makes a good point. For me it is not 'amenities' so much as the really uncomfortable seats on the new OUIGOs. We never book long trips on it if we can avoid it. The TGV even in second class is comfortable; the OUIGO is in our experience excruciatingly uncomfortable.