For newborns, firm is the way to go, coconut coir mattresses are often recommended because they give that solid support little ones need and are breathable in our humid weather. Someone in my mum group swore by Palette Box for their cot mattresses, said the quality is good and sizing fits standard cots well. Just make sure whatever you pick is waterproof or get a waterproof mattress pad on top, saves you so much trouble with leaks in the early months!