I have not used all the warframes but there are frames I have seen and heard that are amazing to see and why not do it for fun =w=
I maybe do a redo of "Warframe Matches Up" Where to see who would win again fun but I don't see it happening XP And finally I did 6 guys and 6 gals to to keep things even(12 Warframes)

Excalibur, the Knight- A classic frame and overall good frame for both new and old players

Nova, the AntiMatter- Fun frame to play with fun abilities as well

Ash, the Assassin- The true ninja in the game

Mesa, the Gunslinger- Stealth not need for this gal, better watch when she enables Peacemaker

Oberon, the Paladin- A frame that deal damage and can help the team

Titania, the Fairy- Just a beautiful frame with amazing skills, cause why not

Volt, the Electromancer- He's not my favorite element focus frame, but he is sure is fun to play with

Banshee, the Sonicmancer- Another amazing girl with deadly abilities and is also assassin like frame

Chroma, the Dragon- With nice abilities and style to help fit in to any fight as of course he is a dragon

Trinity, the Healer- An amazing support that can help you team to stay alive

Zezha, the Dancer- Fire plus warrior style frame

Zephyr, the Windmancer- Amazing Frame with interesting skills

Want to now a little more about them or want to know other frames go here https://www.warframe.com/game/warframes