Suarez in my opinion is better than him simply because of his work rate. If Liverpool get in two out and out wingers in the summer to help supply Carroll it'll mean Suarez can drop deeper like Rooney does to link up play better with Gerrard and Meireles.
Anyone who wrote off Torres is a bit dumb to be honest. There's no doubting his goal/games ratio, the only issue with him was his head would often go or he'd not hold the ball up well enough and fall over a lot which got annoying.
Suarez is the type of player who'd be of value to any team purely because of his work ethic like Park, Hernandez, Kuyt, etc. whereas Torres and Aguero need to be played in the correct system to fit in and be effective.
Look at the work ethic of Chile in the WC, it was unbelievable.
To be honest I wouldn't sign Aguero, I'd look at someone who harasses defenders like Suarez. Two strikers like that in your team like Rooney and Hernandez and it gives you an entirely different edge.