Bucky Brooks examined this seemingly random question at NFL.com, and the result is positive for the Tampa Bay Buccaneers: Brooks thinks Vincent Jackson is a better receiver than Brandon Marshall. That in and of itself isn't all that interesting: the two are very different receivers who rely on different techniques, and a direct comparison is more a matter of taste than anything else. But the story is mostly interesting to me because of the various details on technique and ability. Brooks goes through a number of Jackson's plays to showcase his abilities, and comments on the specific attributes that make Jackson a top-notch receiver. I'll highlight a few of those quotes, but you really should just read the entire thing:

He excels at blowing past defenders on vertical routes, but also displays the ability to outleap opponents for contested balls in traffic.

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Jackson excels at running the vertical portion of the route tree. From the "Bang-8" (skinny post) to the post-corner, he has developed into an indefensible threat in isolated situations with his speed and athleticism. In an offensive system that emphasizes the vertical passing game, he is a nightmare to defend.

[..]

Jackson has developed into one of the best pass catchers in football. He excels at tracking the ball on deep routes and his ability to make last-minute adjustments on errant tosses expands the quarterback's strike zone. Although he occasionally muffs a ball due to a lapse in concentration, Jackson's focus and consistency stands out on tape.

[..]

Jackson is undoubtedly one of the best in the business at delivering explosive plays (20-plus yards). He has compiled an impressive career average of 17.5 yards per catch by routinely getting behind defenders on vertical routes. In addition, he has become a prolific touchdown maker, with 37 scores in 91 career games.