Best:
Declan Nicholas Thomas- my absolute favorite male name of all time is
Nicholas.
Declan William Thomas-
William is my second favorite male name of all time.
Worst:
Declan Mitchell Thomas-
Mitchell has no appeal, it seems dated. I really hate the nickname
Mitch. Way too close to a not so nice word in the English language.
Declan Benedict Thomas-
Benedict seems harsh, dated, overly religious (think pope); just add Hollandaise sauce.