If the fight happened this year, at 140 pounds, I'd take Marquez. At 135, while I'm sure 'Quez could make the weight, I don't know how comfortably he can do it since he's swapped some body fat for lean muscle mass.
So right now, at 140, I got Marquez by late TKO/KO, or a fairly wide UD. While Broner is learning to trust his instincts more, and more since the Ponce De Leon fight (which he clearly lost), and stand his ground strongly in the pocket, and pick shots off, he is still very hittable, and has all kinds of holes in his defense. Broner can roll with shots, and catch shots with his gloves, forearms, and shoulder, but Marquez punches in precise single shots, combinations, and counter-punches with what seems a newfound power at 140+.
Should Broner try to counter Marquez, or even "counter his (Marquez's) counters," Marquez will take the lead, throwing first, and outpoint Broner. If Broner tries to steady walk Marquez down, and somewhat be the aggressor like he's done lately (by trusting his instincts), it's only a matter of time until Marquez finds his rhythm, and his openings, and exploit them - resulting in a stoppage.
In conclusion: Broner doesn't have the wheels to really open up angles, the work-rate to out work Marquez, nor the defensive posturing to prevent getting tagged cleanly. . . At least against Juan "THE BEETHOVEN OF BOXING" Manuel Marquez. . .
Comparisons with Mayweather aside, I think Broner has the makings of a very good to great fighter, but I think that Marquez would be too much for him right now. Unlike Floyd, Broner is an offense first fighter and he risks himself to make the fight. He took some very good shots from Rees and was able to handle them well, but Marquez is not Rees. As the other responders said, Marquez slices and dices with his shots. Mayweather won his fight with Marquez because he was bigger, longer, and he made Marquez fight his fight which was to have Marquez do the chasing. When you put someone in front of Marquez who will move forward or stand in the pocket, then you get a war. I think Floyd fought a perfect fight to be Marquez. Chris John fought a similar fight when he beat (albeit controversially) Dinamita. I don't think Broner has it in him at this point to go defensive in order to take Marquez out of what he does best.
I see Marquez beating Broner by UD.
While I wouldn't call Marquez the "Beethoven of Boxing" he's still one of the top 10 greatest lightweights of all time and among my personal favorites. Marquez wins this fight and he wins it with it authority. Marquez is the old war dog who's seen it all and survived it. He's too strong, smart, and just flat out good for Broner. Marquez wins by of KO in the 5th
broner aint floyd...w/ the way he fought rees....jmm will probably knock him out
Who would win?