From what I’m seeing, no previous Paper Mario game has even passed 5m sales, VGC has the highest one at 3.7m on Wii, and while the Switch effect will likely have it be the biggest game in the series to date, I don’t think it can more that double the sales of the bestselling prior Paper Mario game.

Meanwhile Sony has now had 5 first party games pass 10m sales this generation; TLOU Remastered, Uncharted 4, Horizon: Zero Dawn, God of War, and Spider-Man; with GT Sport at 8m as of last June (possibly tracking to pass 10m) and Days Gone tracking to pass 10m lifetime as well I’m pretty sure. Fairly safe bet that Ghost of Tsushima will be another 10m+ seller for Sony; maybe not on PS4 alone, but PS4 sales combined with the likely eventual PS5 port will almost certainly be over 10m. So yeah, I think Ghost of Tsushima will come out on top.

GoT is coming out during a bad time, so late in the PS4 gen. It has the potential to do just as bad as Days Gone or as good as early Horizon sales as a new ip, but the late release doesn't help.

Switch games tend to do better than their predecessors, so a 1st party Mario game should have no problem.

I will have to go with Paper Mario.

Don’t underestimate gaming buddy,

TLOU came out like 5 months before PS4 came out and it did exceptionally well for a new IP. 
GTAV was a late release, coming out 2-3 months before “next gen” and it destroyed everyone’s expectations by a landslide, even to this date surely every kid and their parents have one each and now who is still buying the game? 

Late releases can be a good thing, like a swansong for a console, the games I mentioned were very well received 

Animal crossing came out during a bad time (covid19) and it blew up, I never saw the surge coming, I knew the game would sell well overtime, I know people that snapped up a switch just to play this game with their friends in isolation.

Yep but GTAV is made by Rockstar, a dev with many high selling games, and is from a top franchise. TLOU is made by ND, a dev renowned for making good games. Animal Crossing is a famous franchise that appeals to many markets.

GoT is a new ip from a dev known for making superhero games that only sell around 3m. It will do well, but not THAT well.

that is a fair point though,

also the same could be said about Guerrilla games as Killzone is around the same mark, just depends on how well marketing is, word of mouth and the critics respond to this game, Horizon sold over 10m and Guerrilla games usually sell less than 3m, a big step up between lost and this gen. 

Switch and PS4 games, whether it’s a new IP or an established IP has exceeded most people’s expectations