A bit more on generation definitions. Another way to approach the matter is to look at what is definitely Lost Gen vs. what is definitely Next Gen, and then try to figure out what the best line between the two is.
I think we can safely say that those players born 1996 or later are definitely NextGen, players like Coric, Khachanov, Medvedev, Berretini, Garin, Donaldson, Kokkinakis, Chung, etc. Why definitely? Because those players were eligible for the first Next Gen Finals in 2017.
On the other hand, I would call 1992 definitely Lost Gen. Players born in 1992 include Bernard Tomic, Jack Sock, Diego Schwartzman, Ryan Harrison, Marco Cecchinato, Marton Fucsovics, Denis Kudla, etc. Harrison and Tomic are two of the most infamous LostGen types, so I think 1992 is clearly a Lost Gen year.
So that leaves us with 1993-95. Here are players born in those years:
1993: Thiem, Vesely, Daniel, Caballes Baena, Novikov
1994: Pouille, Thompson, Coppejans, Pavlasek
1995: Kyrgios, Edmund, Djere, Nishioka, Norrie
That's a pretty weak three year cohort. Ultimately it is a subjective judgement call and just a matter of semantics.