This thread is born largely out of the fact that I won't be able to see Endgame until probably May 11th and so I'm avoiding CBR for the most part so I don't get spoiled. I'm also currently reading the Lensman books by Doc Smith.
So Lensmen vs. GLs. You can go with whichever versions of the Green Lanterns you think are the most powerful: Silver Age, Bronze, Post-Crisis or current. I'll toss out a bunch of scenarios. Respond to whichever you like.
Standard arena match: Kimball Kinnison vs. Hal Jordan. Kinnison gets a DeLameter, a Lewiston, his armor, his space-axe and, of course, the Lens or anything else as long as it would be considered standard personal equipment. Obviously, he doesn't get a ship. Jordan gets his Power ring.
Same situation but with prep.
All-out war. For whatever reason, the Lensmen and the Green Lanterns go to war against each other. They both get prep and start at opposite ends of an otherwise uninhabited galaxy.
The Arisians versus the Guardians of the Universe. No prep, they just encounter each other and the battle starts. I realize not giving the Arisians prep is taking away the very essence of what they are but giving them prep is virtually an auto-win.