Kegs take up less room and for that reason are better in my opinion for long term storage. You can fill bottles from kegs if you need to, but it's easier to just have the mead on tap for your home consumption and to only fill bottles when you need to. If you're filling a bottle to drink somewhere else that night, you can get away with filling it straight from the tap. If they will be sitting for longer, you'll have to go the whole 9 yards with sanitation, probably using a picnic tap or something that you can thoroughly sanitize for making the transfer.
I use CO2 to dispense my mead. I just keep the pressure really low. It does pick up a very slight carbonation over time, and I recently decided to carbonate one mead on purpose. Gives it a more sour and less sweet character, and I found that I like that too.
If you want to have bottles on hand to give out at the drop of a hat, obviously at some point that will mean having to bottle. Since you can easily bottle from a keg, though, and since kegs take up less room, you could keep everything in a keg until you're ready to bottle. Less chance of bottle bombs that way, among other things. The one thing you have to pay attention to bottling from kegs is the fact that the mead is getting drawn from the bottom, which is where the yeast settles. If you don't modify your dip tube that will mean getting some cloudiness in your first bottle or two. You can avoid that by shortening the dip tube so that it draws from above the yeast, though then you leave more mead in the keg. Neither approach is perfect, though you have essentially the same options bottling from a carboy, so it's not like you're worse off in this respect with a keg.
