Are we talking middle school or high school? If high school, Boys or girls?
If high school boys, neither is impressive at all.---The question shouldn't even contain the word "impressive". Maybe instead: Would I make varsity easier with a sub 5 or a sub 12? Of course the answer would be "the same". Neither would get you on varsity.
A better question might be: is a sub 4:30 more impressive than a 11.6?---A legitimate high school boys performance question.