Fine fill and scratch fill Axalta 705 (professional auto supply). Can be sanded in 15-45 minutes depending on putty depth on resin. On plastic it takes longer as like all solvent putties it softens the plastic a little.
Contrasting color for fine fill Tamiya Basic.
Joint fill where detail is close and I want to avoid sanding 405nm UV curing resin applied with a needle and cured with either a UV laser or UV flashlight. Sands just like plastic and is of course instantly cured so no waiting. Also using it to attach PE rails. It worked great to fill the gaps at the wing roots of the Roden 1/48 Junkers D.1. and required no sanding there as I did not get any outside the gaps.
For ships I should note I build mostly old resin kits vs. plastic kits.