But if it's a question of the cheapest - "bang for the buck", or whatever - then that would have to be warm soapy water and a washing-up sponge (soft on one side, mildly abrasive on t'other). And for the
purists out there ... this is the method almost always recommended by manufacturers, as well. Add a few grains of Daz (Tide)* or even Ajax (Vim)* as necessary.
Another one (for crud ingrained into a scratched surface) is a dab of Mr.Sheen* (again) or one of those sink (bath) cleaning creams (the lemon fragrance is always nice) and a rub with light grade Emery paper.
Needless to say, T-Cut (when skilfully applied) also has its uses, especially when "refurbing" kit, or getting paintwork on old stuff presentable (for sale, or donation, for example).
*
Many other easily found household cleaning products are available.
