First of all, be aware that i'm a big fan of United and Liverpool, way more than i'm fan of Arsenal.
Of course Arsenal would get less media than both of them. Most of people voting there are kids/clueless people who started watching football recently.
They are going biased for Klopp's Liverpool because it's the only team most of them have ever seen play, or have seen way more than the Invincibles.
Imagine, like some random page makes a votation
Eusébio's Benfica or Real Madrid's galactics?
There would be like 70% for Real Madrid, even though they hadn't won a single CL, and never deserved it though.
Comparing their current squad to the Arsenal's invicibles is pretty much of an absurd to be honest. Pay attention to the current state of the Premier League:
Arsenal - Bad phase, emblezzlement
Tottenham - Bad phase, no titular GK, new coach + emblezzlement + adaption
Chelsea - Bad phase, adaption, emblezzlement
Man United - emblezzlement, lost both Lukaku and Sánchez in a single season, +++ adaption, worst season of them in PL since 1997/1998 agreeing to stats
City - No Sané, No Laporte, and when they were against Liverpool in Anfield, no Ederson, no Mahrez and no Rodri. Guardiola in a bad phase.
Not that Liverpool doesn't have merit, but once they got a strong team like Napoli, they struggled in their own home against them, and lost 2-0 in Italy.
Imagine a post champion like that playing the round of 16? It would be 3-1 for Napoli.
They conceded 3 goals inside Anfield against Salzburg, barely lost... fragile defense sometimes. They showed that against Watford(back then they were 20th place), Liverpool 2x0'd them in Anfield but two strikers lost it 3m away from Alisson and with a giant angle to shoot. They choked, coulda been 2x1 for Watford.
They almost lost to United in Old Trafford as well that was terribly struggling..
They are soon about to get exausted just like Arsenal did in 2003/2004 and consequently lost the Champions League.
Arsenal played a period where United was in their prime and almost won 2003 champions League, Liverpool was in their prime as well, next season they'd won the title. Same for Chelsea when Frank Lampard was considered the 2nd best player in the world 1 year later, not to mention Newcastle's Shearer(stronger than 2015/2016 Leicester imo).
Don't overrate Liverpool that much.