I like wood better, it looks nice and more natural. Unless there is a need for a metal deck (something that lasts longer) then I would rather prefer that. There are ways to make a metal deck look better though (carpets, fake wood prints, ect.)
I will be building a deck next summer and have not made up my mind what material to with yet. I am pretty sure it will not be metal though I stepped bare footed on a metal deck once and only once and never want to do that again. also I am not sure about wood either because I am still considering all the options.