IMO, both are options... I'll probably end up bottling BIG brews that will benefit more from it, or that I want to stock away for later. Not to say that I'll carbonate with sugars there though. I like the control I get with carbonating via gas.
BTW, you CAN have the best of both worlds, carbonating batches in kegs, then bottling from those kegs and keeping them around for the long term. Once you have the desired carbonation level (so much easier to fine tune in keg) you just bottle it up (Bowie Bottler and wand is one easy option) and set them aside. You now don't need to worry about uneven carbonation, or bottle bombs developing.
As for the head from kegged brew, you can get the same as from bottles, IF you chose to. Use a faucet like the Perlic 575 'Creamer' and you'll get the head you wish in glass. Get the stainless version and it's something you can pass down to your children. You can also put brews on beer gas, getting the infamous cascade effect and rich, thick, head (like you get from a properly poured Guinness).
IF you don't rush your brews through the process before bottling/kegging, then they'll be identical in bottle/keg. Since I go with the long primary method, my brews are ready for drinking as soon as they are carbonated (the ones that don't NEED extended aging). I'm more of a mind to let a brew age in batch form and then bottle it when it's actually ready. IMO, that's better than bottling earlier and having to wait for them to bottle condition/age before they're really good/great. I have enough vessels to ferment/age in that it's not an issue for me.
Also, it's been documented that brews age better at lower temperatures (more stable). So having a keg in the keezer/kegorator/brew fridge for aging (IMO) makes a lot of sense. I intend to do that with the next big brews I make (over 10%). I'll purge them of air, with CO2, and then leave them disconnected from the gas system. I won't be looking to carbonate the brews at that time. Later, once it's ready for consuming, I'll carbonate to the level I desire and put it on tap. OR bottle it up. OR both...
Personally, I like having the flexibility to do either/both methods. I'm NOT pushing my brews from grain to glass, accelerating the time frame by rapid force carbonating. IMO, when done RIGHT, both are valid choices across the board. Neither is 100% the best method. If YOU chose to use just one, good for you, just don't diss people that choose to use both, or the other.
In the end, serve out of whatever you wish. If you only aspire to bottle your brews, forever, then go for it. I'm sure you'll be happy with that. I've seen enough posts where people are whining about bottling a couple of 10 gallon batches in a day/weekend. If you wish to use kegs, just remember that SOME brews will be better in bottle. Or easier to gift that way. Having a way to do both is of value. Just pick the containment method that fits the brew.