only case that would be true is if you live in a country where GoG offers you regional pricing Steam doesn’t, otherwise prices are basically 1:1, incl discounts
one of the reasons for this is Steam straight up demands price parity, like other businesses do, going back to the days before Steam was even a thing
i’m told for some Epic games are also cheaper than steam because they offer a broader range of regional pricing than Steam’s very rudimentary narrow brackets, but in $, € £ etc etc where regions/currencies overlap, a game also costs 60$ on Epic, like on GoG, like on Steam; Valve wont let you sell a game on their store if you have a cheaper base/fixed price elsewhere
as for user service/customer service that will always be subjective, GoG def has a lot of upsides, but also some downsides; they don’t get all games because some publishers are dicks and demands DRM
also worth to note, not all games on Steam has DRM, not even necessarily the “default” Steamworks drm
https://www.pcgamingwiki.com/wiki/The_big_list_of_DRM-free_games_on_Steam