For the long haul, I prefer free standing vanities. Down the road, when I might want to replace the old one, a freestanding gives me more options. If I've got a built-in, that means there's just a sub-floor underneath. Plus I just like the furniture look of a free standing vanity.

this is a beautiful look but how do you clean in the small spaces at the end of the tub?
love the look of the floating vanities!!!

I prefer free-standing vanities.

I like both well enough, it really depends on the space. I have a built in because it maximizes the small space that I have. It works for us because we don't have additional space to clean underneath or in-between. I would put a free-standing vanity in a guest bath though.

Freestanding of course. Especially when it's an antique.

i do enjoy the variety that both provide. i love a great built~in...but there is nothing like customizing with a wonderful ole antique and a hand blown vessel for a sink.

I prefer vanities that are wall-to-wall with tons of storage - preferably suspended above the floor such as the one in the photo, but at a height that's appropriate for the occupant, as most are mounted too low for my tastes (I prefer a 36" high vanity)...
...and I hate vessel sinks - they're a pain to clean and are going to be one of those "Oh, this bathroom was redone in the 2010's" sort of things - Give me an undermount every time so I can just sweep the splashed water in to the bowl.

I agree with bepsf--vessel sinks are going to date the room for sure. But do you think granite counters (and stainless appliances) are going to do the same thing?

Yes, I believe that Stainless Appliances and Granite (particularly black granite) are the Harvest Gold and Faux-Butcherblock laminate of our time...

...but classic White or Almond Appliances - no matter how old - never jump out at you and say "Guess what year I was purchased?" Along the same lines, real wood butcherblock countertops and stones other than granite such as marble and soapstone have a timeless quality about them that granite just doesn't.