His speed was incredible and was one of the very best dribblers of his generation.
True - but that doesn't make him
historically great (which was my point). Neither his speed, nor his dribbling ability, nor his ability to carry the ball at a high speed - make him stand out in an all-time context. There are multiple similar players (wingers) which by common consensus would be rated higher than him.
Beckham, on the other hand, does stand out with regard to his most obvious quality: as a pinpoint crosser he compares to just about anyone. He has significant weaknesses, of course, which means you wouldn't choose him in an all-time XI over any number of players (he was slow compared to a great traditional winger, for instance - and not a very impressive dribbler) - but his crossing ability was truly extreme.
Giggs has no
extreme qualities in an all-time context.
Or rather - he does have one: which is, again, his longevity at a very high level.
Scholes is similar. He also remained a very good player until he retired well into his thirties. But his extreme qualities (passing accuracy and range - and general "awareness") were more impressive than Giggs' (speed, dribbling) AND he retained those qualities on the highest level for much longer.
Giggs obviously wasn't anywhere near the fastest or most effective dribbler in the world at 35, he was just remarkably good at it for his age (even more remarkable at 40). Whereas Scholes was an
insane passer - compared to anyone - even when he came back from retirement.
Giggs: Extreme quality/qualities: nothing special
historically.
Scholes: Extreme quality/qualities: special but he doesn't positively stand out (there are a number of other players who offer the same, and who are arguably better on the whole).
Beckham: Extreme quality/qualities: special, even historically (there aren't a number of players who offer the same, he's in an "elite" group that doesn't comprise all that many).
Before anyone jumps to the wrong conclusion: this doesn't mean I rate Beckham as either a better player, all things considered,
in his prime OR that I rate him as a greater United player than either Giggs or Scholes.
On the contrary, based on ALL factors, my list would be:
1. Giggs
2. Scholes
3. Beckham