I think SQ flies mainly 777-200 between SIN-KUL with 2-3-2 seating

MH uses both wide-bodied planes with 2-3-2 seating and 737s seating with 2-2 seats

Do remember that even on with 2-3-2 seats, these are regional business class flights. It is only called First due to an historical agreement between the two governments. You do get Tier Points and Miles for F travel ^

The trays, linen, cockery may be F but the rest of the service is F.

Snack on SQ is better. MH offers a selection of spicy Malaysian snack which does put some pax off.

This flight is so short, it is really the lounge facilities that drives choice.