They are all very good singers. But I think both Woohyun and Sunggyu are the best singers out of all 7. But i cant say both as my answer so...if i had to choose one of the two i would say Sunggyu. Reason why is because,like how i said in one of the past chapters about who my favorite Infinite member was, his voice is just amazing~

This is one of my favorite vids of him singing ^^ 

Sorry Namster, but Sunggyu wins this round cx