As good as De Bruyne?! I'm a United fan and understand there will be a bias, but come on!
He had an unbelievable ability to kick a ball to an exact spot, down to an inch but apart from that he wasn't that great. I remember constantly being annoyed with him when he wasn't taking a beautiful free kick.
He didn't have any pace, wasn't very skilful (apart from his obvious ability to kick long distances), couldn't defend, wasn't a fighter when needed like a Keane or Rooney, etc.
The media status he had/has probably makes people people remember him more fondly.
Its not really bias by United fans at all. He was 1st runners up in Ballon D'or once and 1st runners up in FIFA world player of year twice, something which 29 years old De Bruyne hasn't quite managed yet (his best season is 9th in Ballon D'or, 5th in FIFA awards). He was also PL top assist in 3 seasons, so his stats is also up there with the other best midfielder. His inc perfect crossing and long pass is just out of this world, and has won us many points. Imagine if teams like Juventus have peak Beckham this season, players like Ronaldo even at 36 would be easily scoring 50+ goals. "Bend it like Beckham" is really a thing back then. Apart from his worlclass passing/crossing/freekicks, he also has top class workrate.
But for sure, there are some distraction when he was focusing more on his brand in later years. But he still has great career, winning total 17 trophies for Man Utd, Real Madrid and PSG. De Bruyne has won 15 trophies for City, Wolfsburg, Genk. So their career is actually comparable in every sense.
Trophies won in Europe*: Beckham 17 >= De Bruyne 15 (or 16)
Ballon D'or: Beckham (2nd place) > De Bruyne (9th place)
FIFA best player: Beckham (2nd place x2) > De Bruyne (5th place)
CL: Beckham 1 >= De Bruyne 0 (or 1)
WC: De Bruyne (3rd place) > Beckham (quarter finals x 2)
Euro: Beckham (quarter finals) = De Bruyne (quarter finals)
International*: Beckham (17 goals 115 caps) = De Bruyne (21 goals, 80 caps)
Best season: De Bruyne (16 goals 20 assists in 48 games) > Beckham (16 goals 8 assists in 43 games)
Career stats*: Beckham (127 goals 205 assists) = De Bruyne (113 goals 190 assists)
*De Bruyne is still playing, at 29 he still has at least a few more years playing and winning at the top, so things could still change in future. But as of this point, Beckham is just slightly ahead (but they are very close).