The one most widely available is 'Total Shaving Solution' which isn't the best one.
If you can find one in a coloured bottle, dark blue, with a spray top, get that one. Tesco have it sometimes. Its full of essential oils etc... also the oil evaporates if you forget to put the lid back on, but with the spray cap bottle, that doesn't happen.
I use shaving oil all the time for facial shaving, much better than foam or gel, no dry skin, no flaking, no burn.
I actually only shave 'downstairs' sporadically, or if the current 'squeeze' requests it.
It does however, truly make your todger look bigger.