I was an avid "thicker" string user, until I went to GC and tuned down a 6er with the stock strings to D standard; and found the guitar a lot more "playable" and I liked the tone much better.
It definitely comes down to preference, overall, but I must say... I used heavier strings for the last 6 years, and switching to the lighter gauge felt much more natural. But again, that's just me.