Both great players but it's ridiculous how people still consider this to be debatable.
Aguero: runs like a bull, but with head down and into pressure. Not a creative dribbler and very frustrating/makes things difficult.
Suarez: slippery as fuck to contain while dribbling. Capable of pulling out megs, cuts, bursts of pace, etc. at a moments notice.
Aguero: tough, bullet-like shot that's often accurate at getting into the corners when he has space to pull the trigger.
Suarez: wicked cannon that can manifest regular golazos. His freekicks have brilliant curve and power, his long range strikes are often unstoppable, even his headers are somehow extremely strong. Plus, he can do it under more difficult situations (like the longball->first touch with chest->finish)
Aguero: creativity is meh, doesn't have vision and doesn't produce moments for others. He has the capacity to assist but assisting isn't creating.
Suarez: dynamic and brilliant creativity much like Messi does for his teammates in buildup (not same level though). Has that subconscious and instinctive sense of brilliance (like Messi, Ronaldinho, Iniesta, etc.) whereas Aguero just does what he knows and is a more trial-error-refine/repeat type of player.
Suarez is just a superior overall footballer, plain and simple. It's like even though Messi/Ronaldo put up similar goal numbers year to year, Messi whoops him in multiple facets of play. Suarez has been brilliant for a few seasons now and can continue even further, he doesn't have the merit of some of the most elite players but he does not lack in ability.