Now before we start, we know this is always a hot topic.
Football fans always like to think their club is the biggest and the best, that's why supporters from Accrington Stanley to York City sing about being "by far the greatest team the world has ever seen", and we wouldn't have it any other way.
There are some clubs who are much more popular than others though, and we're about to see two of them go head-to-head at Old Trafford on Sunday.
Manchester United vs Liverpool is always a standout fixture in any season. It is a collision of history and culture, and of success and expectation.
People from the two cities don't like each other, even though they are a lot alike in many ways, but their football teams are renowned far beyond the city limits.
In these days of multiple revenue streams and European Super League proposals that matters, but just how these clubs' many, many fans around the world staying connected with their team?
Well, ahead of United facing Liverpool we've taken a look across five of the major social media platforms - Facebook, Instagram, Twitter, Tiktok and YouTube - to see just who are the most followed teams around the world.
It doesn't prove anything of course, but it is an interesting thing to keep track of.
Ready then? Try not to get too angry. It's just a bit of fun. Be nice in the comments section.
Information correct as of October 21, 2021.In instances where clubs have numerous social media accounts in different languages, we have only included their main account in the results.
10. Arsenal - 81.2million follows
They may not have had much success on the pitch of late, but Arsenal's claim to be seen as a 'super club' - something we all questioned in April - can be backed up with their social media presence.
The Gunners built up a loyal fanbase during the glory years under Arsene Wenger, and although they have now gone some 18 years without winning the Premier League title - with surely a few more to come - their supporter base shows no sign of dwindling just yet.
9. Manchester City - 87.6million follows
They may regularly face jibes from rival supporters - and sometimes even their own manager - for an apparent lack of support at the Etihad Stadium, but City are beginning to turn heads online.
Their 41.2m Facebook followers is only bettered by Manchester United and Chelsea in the Premier League, while they beat the Blues on YouTube and have the same number of followers as them on Tiktok - some 4.9m people.
8. Bayern Munich - 97million follows
Enormous in Germany, and well-respected everywhere else, Bayern Munich have long been established as the dominant force in the Bundesliga and a pretty handy one on the continent too, where they won the Champions League in 2020.
Their worldwide appeal comes from almost constant and sustained success, with their 54.1million Facebook following the largest outside of the top three on this list.
7. Liverpool - 103.1million follows
Following a fallow period by the club's standards, Liverpool supporters have been energised and reinvigorated by the club in recent years under Jurgen Klopp.
The 2019 Champions League win and then the long-awaited Premier League title the following season created some of the most memorable moments and images in the club's storied history, and their status as one of the most supported clubs in the world has long been established.
6. Chelsea - 107.5million follows
The current champions of Europe received a big boost in their followers when they picked up the continent's biggest club prize earlier this year, and the fact that they rarely go a sustained period without picking up a trophy or two certainly stands them in good stead when it comes to attracting new followers.
Thomas Tuchel's appointment as manager to replace club legend Frank Lampard earlier this year has turned into a masterstroke from owner Roman Abramovich, and he'll be delighted to see the growth of the club since he bought them in 2003.
5. Juventus - 115.2million follows
Cristiano Ronaldo may have gone but Juventus live on, even if the Portuguese's summer departure might have cost them a few follows across the various platforms.
The Turin giants were the undisputed masters of all that they surveyed in Italy prior to last season, when rivals Inter Milan ended their nine-year run of winning the Serie A title.
4. Paris Saint-Germain - 143million follows
By our - fairly rough - estimations, Paris Saint-Germain's summer signing of Lionel Messi took them from seventh on this list to fourth, with the addition of one of world football's most recognisable faces seeing them jump above Liverpool, Chelsea and Juventus.
Messi may still be getting used to life in the French capital, but the interest in him continues to be huge.
PSG's Tiktok account seems to have been the one which has grown the most since the signing, with the 20.5m followers it boasts now ahead of everyone else in the list - including the club Messi left behind when he moved to France.
It will be interesting to see if interest in PSG extends after the Argentinean has moved on, especially as Kylian Mbappe seems set to leave soon.
3. Manchester United - 168.5million follows
What Juventus lost with the departure of Ronaldo was seemingly gained by Manchester United, who outstrip all of their Premier League rivals to take third spot on the list.
Their Facebook following alone is almost twice that of 10th-placed Arsenal, and it was no wonder they rushed out every piece of available Ronaldo content following his return to the club after 12 years away.
2. Barcelona - 269.6million follows
Things might not be firing on all cylinders on the pitch at the moment, but off it Barcelona are still in rude health - in the social media side of things anyway.
An enormous following has built up across the five platforms we've looked at, including a huge 12.5m subscribers on YouTube, a number that dwarfs the rest of the competition.
1. Real Madrid - 270.7million follows
Just pipping their great rivals to the post by some 1.1million followers, it is Real Madrid who take the crown as the most popular club in the world.
The Spanish giants and 13-time European champions have the biggest following on Facebook, Instagram and Twitter, and can quite understandably claim to be the biggest club on the planet at a result.