My wife just bought me a used Electra Townie with aluminum frame and wheels. The previous owner claimed it had been serviced in the past year. Checking the bearings, I can tell it was a poor job of lubrication, probably done by the seller using who knows what for lube. What lube(s) are proper for the various bearings, etc on this bike?
Cup and cone bearings on a bicycle need 'preload' for them to work properly under load. This is because the balls are tiny spheres of metal that deform under your weight. Hence the bearings must be tightened up slightly beyond feeling smooth when unloaded. Due to quality of parts, i.e. not perfect, a pre-loaded bearing feels 'rough' and requires effort to spin it. There are proper ways of applying the correct pre-load, e.g. with the use of a torque meter, however, 'feel' is a good way to do it. To understand that 'feel', go into a bike shop and try to turn the spindles on the new wheels that are for sale. With rare exceptions all of them will feel rough - this is preload. Now see how your own spindles/axles feel when you turn them without load, chances are that they feel pretty much the same.
If you have rough bearings then you might think the grease is missing. Chances are that it is just the preload and not a grease problem at all. If you are going to dive in there anyway, do get a handle on the preload concept. As for your question on grease, a little grease goes a long way and you don't want it contaminated. The white lithium grease in a tube from your local bike shop will do fine. Yes you can buy posh coloured 'marine' grease but preload is what matters most with bearing setup.
Any standard bike bearing grease will be fine. There are several premium brands such as Phil Wood, but whatever the LBS has on their rack should be as good in 99% of the cases. More important is removing any traces of dirt, which generally means washing the bearing pieces in solvent.
As stated, properly tightened bearings will feel ever so slightly "gritty" when you turn the axle by hand.
I do not want to go into brand recommendations, but any general bike grease should be fine. I have good experience with Motorex Bike Grease 2000 (here goes brand recommendations), but really, this is not rocket science and you cannot do anything really wrong. Just clean it, put enough grease there and you are good to go.
I suspect that the grease used before was too old and had started degrading.