Who I would have put in a Boukenger vs Super Sentai Gokaiger episode

Gekiranger
GekiBlue: The most serious and smartest of the original 3. His brother is GekiViolet.
Toei probably would have put:
Gekichopper
He is definitely an improvement and stand out from Jungle Fury.

Go-onger
Go-on Black easily the coolest of the Go-ongers, although campy himself.
Toei probably would have put:
Go-on Green in a similar teamup, and I would not have complained either. Both really stuck out as the bad ass-suck up combination.
The Go-on Wings would probably work really well as well. Why did Toei decide to underfund the toy/suit division that half decade? Tired from Deka/Magiranger teamups? They definitely could have added the team to 6, missing previous warriors.

Shinkenger (inclusdes who Toei should have put)
Shinken Red should lead them. Kaoru Hime did a great job in the X GokaiBlue episode 10-11, so she would be a great choice.
I personally like ShinkenGreen a lot, maybe because I am a pseudo Otaku.

Goseiger:
Gosei Pink. I do not know about you, but her cheerful personality stood out for me. Alata is not comparable with any of the Shinken Reds. Gosei Yellow and Black really did not stand out either being twins. Gosei Blue was a smart one, but not as much as GekiBlue.
Who Toei Chose: All of them, though not much stood out for them.

They probably could have added anybody from Deka, Magi and Bouken and people would have been happy as well.