I think raised bars are a waste of work space and when entertaining I often put munchies on the space so the bigger the better.

In a smaller kitchen I prefer counter height as I think it feels more open.

I think the current "modern" view is to have flat island. I have a bar and have been toying with a remodel that will do just that. I hesitate because I have a number of items like a rolling pin, salt and pepper, utensils, pile of saved mail, tissue box etc. that would no longer be hidden....or would have to find a new home. I also don't like the look of counter height chairs. The proportion feels off. It is a tough choice. I'm waiting the fad out and hope to keep the bar.

Having a flat island (or bar) is very functional for serving and eating. It opens up the area as well, as having a raised serving bar 'cuts off' the island.