Board Game Arena

Seems some players play that game quite seriously ... what is the best player count for a "competitive" approach?

Also any thought on L.L.A.M.A party, there's conflicting opinions on whether it's better or just more chaotic

I think the more the better. Because of the quit round mechanic, you get a taste of all the player counts below the table count, and need to adjust accordingly. The quick three player games in Arena mode may be a realistic choice for a game that isn't particularly popular, but such matches are rather stereotyped.

The poll in BGG says it’s best at 4

Definitely 3!