In case you're wondering "Why just these 5?"
It's because in the Ps1 version (and I guess in the Pixel Remaster version as well), you can't change your team at the end and are forced to take a party with these 5 to fight Zeromus. That's why.
Anyways, as much as I love Edge and his fast attacks and him throwing knifes and weapons, I got to go with Rydia. As a party member, she was always very good (everyone is very good if I'm using Rosa or Tellah as comparison tho, but anyway), even though she lost her white magic (which is very sad honestly). What can I say, summons are AWESOME! And Black Magic is awesome too. If I'm being truly honest, my decision is also a bit influenced by Record Keeper, where whenever I use Rydia in my party, as long as she doesn't die, she easily beats the enemies after I use one of her Soul Breaks and then start spamming Leviathan around. It's such an amazing sight.
Oh yeah, and keep in mind I said "as a party member". I'm directly referring to them from a gameplay point of view, so you can kinda throw character development away for this poll.