with prep time maybe doom is able of pulling this one, but if he ran into a GL in the corner of a street, he would loose.
GL is from DC doom wouldn´t know what he´s capable of.
i think GL would won the battle and Doom the war. in they´re first fight i think GL would beat him, yes he doesn´t know doom but he has the power of his imagination, he would take him out (in my opinion). Doom seeing his not able to pull this one runs away, preparing himself for the next confrontation, and when that happen he would beat the lantern.
Doom is far more unpredictable than GL...its not likely Doom would just try blastin GL with force bolts...he's Doom not Blastaar...even his base armor would prove a challenge to any energy wielding opponent like GL...Im not trying to say this is an easy win for either guy...however just saying "GL obviously kicks Dooms ass" is a ridiculous statement and isnt backed up by anything. If Doom's armor is sufficient to engage Tyros with Silver Surfer level cosmic energy then he would be no push over for GL...regardless, how many times has Doom demonstrated it was easy for him to simply steal the power of characters more powerful than GL...Silver Surfer, Galactus, The Watcher, the Byonder, a failed attempt on Hyperstorm and Onslaught for the sake of the story...GL is far weaker than all of these characters...it would probably be relatively easy for Doom to steal his power...Furthermore, when has Doom ever been easily defeated?...certainly not by a single mid tier narrow minded hero like GL, with vastly inferior intelligence...when has the actual Doom (not a doombot) been put into submission with certainty? by the Fantastic Four, By the Dreaming Celestial, By Hyperstorm...Never by a guy with slightly higher than normal IQ...Reed Richards and Hyperstorm are two of the greatest genius in Marvel...and a Celestial? a being almost as old as the universe and created by Eternity/ the BEYONDERS, is pretty damn smart...no incarnation of GL has the necessary intelligence.
Doom would whoop his ass and then steal his ring...and then conquer the DC earth.
You don't really have to make a "prep time" argument. None of the Green Lanterns would kill Doom on the first pass, thinking that they defeated him...unfortunately it's naive to think so. Doom would come back, steal the ring, kill the GL, kill the rest of the GL Corp when they came after him, steal the power from the Lantern HQ, kill the guardians, take over the planet, and then would have to man up to Hal Jordan, aka, the Spectre.
Now THAT is a match. Doom with all that power vs Spectre. Damn...imagine that, Doom with Parallax's power.
I may be letting my imagination run rampant...but Doom still takes it.
Now, I'll take the opportunity to defend GL. Gl's not a mid-tier character (or shouldn't be anyways), GL's a character that should be up there with Superman, Batman, and Wonder Woman on the JLA roster. Now, Hal was sort of on that spot, John, Guy, or especially Kyle never got that far up though, unfortunately. So put simply, the Greeen Lantern character isn't mid-tier at all, although the person who wield's a ring might be, which is the exception. With that said, Doom still wins, in my opinion. If it's the newly returning Hal, then Doom has much more of a fight.