Jack Landors and Banban Akaza- While some people dislike Banban Akaza for being a fireball and a screamer, but to be honest, I like Banban Akaza way better than Jacy Landors. Jack Landors was quite an opportunist who slacked off the obstacle course (but he did it at the end of that episode) but Banban Akaza would have gone through it without complaining and doesn't skip training. Banban Akaza is the more enthusiastic and more explosive. Also, Banban Akaza's involvement in getting Gyoku Rou (though he did recklessly pluck Numa's feathers which is bad, very bad) managed to get Hoji Tomasu and Marika Reimon back on track. And deciding to become part of Fire Squad rather than resigning for Banban Akaza provides a way better story IMO than Jack Landors' resignation from SPD.
Sky Tate and Hoji Tomasu- Both are professional snipers with a distrust for the red ranger of their series each with their own arrogance that dies out. While Hoji Tomasu was more skeptical because he was under Gyoku Rou, Sky Tate had the issue of wanting to become the red ranger because of his father was one. Both did show moments of being annoying but IMO, Sky Tate had shown more annoyance (like being rash to judge the android girl but he later admits he's wrong) which eventually dies out as he develops. While Hoji Tomasu listens to advice from Sen Enari, Sky Tate had the bad habit of not being open to Bridge Carlson which he later found out was wrong but then, it's very easy to get skeptical over somebody who annoys you so much and I'd be in the same error too if I were him. So while both of them can get annoying in some way but they both deserve credit for revealing the nice guys that was long hidden in them in the long run.
Bridge Carlson vs. Sen Enari- The difference is how one is accepted over the other. Sen Enari is well respected by Hoji Tomasu while Bridge Carlson gets some sort of belittling by Sky Tate (and he's right where Sky Tate is wrong). However Bridge Carlson does annoy me with his mannerisms so I'm siding with Sen Enari. Hmmm... I think Sky Tate isn't going to bash Sen Enari that much, or not at all.
Elizabeth Delgado vs. Marika Reimon- This is kinda biased, really for me to talk this over. Well I think Marika Reimon's story of being a loner picked up by Doggie Kruger is better than Elizabeth Delgado's being a Robin Hood at the start. But both of them had their own character development. IMO I like Marika Reimon's character development better. However the Robin Hood past was also a nice story too.
Sydney Drew vs. Umeko Kodou- Sydney Drew's obnoxious attitude, overacting and a person who doesn't take the job seriously is so annoying but she does change for the better though. Umeko Kodou may annoy Hoji Tomasu (that's because she tries to be the leader when she isn't) but she does take her job seriously at all times so I pick Umeko Kodou instead despite her being airheaded.
Sam vs. Tetsu Aira- The whole ball of light thing is annoying me. Also, Tetsu Aira's got more character development than that so he wins.
So that's just my tidbits, no offense okay?