A third subvariant: Player who win earn points according to how many kings the winner have + 1 (number of kings that the loser have is not relevant), and then add another + 1 if you win by checkmate instead of stale mate. Therefore player with more king earn more points, but only if you win; if you lose, then it is worthless. You can then also allow kings castling with any rooks horizontal/vertically away (even disregarding the other FIDE rules of castling), which does not changes the pieces; this might be a useful move in a few cases.
A third subvariant: Player who win earn points according to how many kings the winner have + 1 (number of kings that the loser have is not relevant), and then add another + 1 if you win by checkmate instead of stale mate. Therefore player with more king earn more points, but only if you win; if you lose, then it is worthless. You can then also allow kings castling with any rooks horizontal/vertically away (even disregarding the other FIDE rules of castling), which does not changes the pieces; this might be a useful move in a few cases.