5) Caitlin Snow

Caitlin is very kind-hearted and the absence of that trait makes it feel like she wouldn't be a part of the show. She was able to adapt to losing Ronnlie when he was presumably dead. Then she was still able to losing Ronnie when he actually died. Killer Frost isn't who she is. I'm glad at the end of Season 3 she was able to change. I hope she can use her powers for good and return to Team Flash.

4) Wally West

Wally West was brought into the show in a harsh way but he was able to deal with it. Realizing who is his father was and that he had sister after his mother died is pretty hard to deal with. His personality was able to deal with it in a positive way. He finally got his speed force powers like he did in the comics as shown in Season 3. I hope he can contribute to Team Flash as much as The Flash did.

3) Eddie Thawne

Eddie's personality was the best. It was pretty hard to hate the guy. He sacrificed his life to erase Reverse Flash(Eobard Thawne) from existence. This last action from him reinforced his personality that the characters or the viewers of the show won't forget.

2) Leonard Snart 

Leonard Snart lived as a criminal but died as a hero. This act shows that he could change and that deep down he had some good inside him. This act made ones who were close to him a better person like Mick Rory. Mick Rory and Leonard Snart became better people when Leonard Snart sacrificed himself.

1) Cisco Ramon

Cisco is the funniest character on the show. His nicknames for villains are the best. I can't see him as a serious person even when he is in his Vibe suit. His powers are amazing and they are suited perfectly for him. I don't want to see him change. He has the most optimism in the show. Its pretty hard to dislike Cisco!