I can't pick! I like watching Infinite dance. Plus they're really good in variety shows and their songs are catchy. BTS is adorable and I love their songs and their random Bangtan TV vids. EXO has multiple members that are talented plus they have really strong vocals and dancers. Big Bang has really good songs and videos plus they have really good rappers.
And, and, YOU CAN'T MAKE ME CHOOSE =_=

well you're asking a site full of ARMIES so...your results are going to be a little bit biased... :P