sarah was awesome too until she lost her memory

Yup

Obviously Chuck! :)

Well, I'm going to look beside the fact that both Morgan and Sarah began to lose their memories and how Chuck started to get mentally unstable (not exactly my words) and with that it makes it easier to judge who I liked being the Intersect the most.

Sarah was incredible as Intersect and I completely understand why she downloaded it. Casey and herself would have died if she hadn't done it but in the end, she doesn't really need it because she's a very talented spy herself.

Morgan was sweet as Intersect and I don't mean when he started losing his memory or the way he behaved to everyone but it was sweet how he wanted to save the world and if there haven't been a virus on the Intersect he downloaded, he would probably have been good with it.

Chuck was complete with the Intersect in his brain because he could control himself and not let the power get to his head, instead he listened to Sarah and Casey and saved the world with them unlike a certain best friend when he had it. Chuck became an extremely great spy by getting the Intersect and with his intentions and his team. He's the best. He needed the Intersect, he got it and end up being a true hero to me :D