I use either grease or a few drops of chain oil.
There are some cables and housings, however, that are not supposed to have lube added - I believe Teflon coated cables and the old Gore RideOn cable and housing sets are examples. Any plain cables can and probably should be lubricated.
Also, while Phil's claims their grease is specifically for bicycles, it is really just waterproof grease made by some other manufacturer and repackaged by/for Phil's... I buy 500ml tubs of 'waterproof trailer grease' at Canadian Tire and it looks and performs very much like Phil's, but at ~1/10th the cost.