Maybe it's because I come from a diddy country and don't have any vested interest in an individual club, but I would certainly sympathise with picking an individual club or league at the expense of others to focus on. The relative diddyness of the football I'm mostly interested in certainly has a much greater sense of relation to me in that the clubs and the national team represent where I'm from and I would naturally have more of an interest in those with them having been present throughout all of my life. Football as a sport itself plays a similarly prominent role in national cultural self-perception and identification for my peers and in general, so if it's natural for me to have a keener interest in that collection of football - making no consideration for the actual merit of the content - then I would imagine the same holds true for anyone who has lived in a country where football is prominent or who moved to/lived in such a country where they became interested and focused on the game and went through a similar process.
With regard to people taking interest in leagues/teams from different countries, this being a predominately North American board I can see a reason for a certain myopic viewing of what constitutes a worthwhile viewing experience. North American sports are largely self-contained and the absolute peak of their professional levels - mainly because, hockey excepted, it's the only continent where these sports are played. Even the comparatively (compared to club football often pre-dating the 20th century) new nature of the transient franchise system in these North American sports creates a view counter to that of the traditional multi-generational football supporter, contributing instead to a desire to watch the "best" league or the "best" players and to subsequently defend it as the "best" at the expense of all others. I've no idea what anyone here or elsewhere in the world lives with in terms of exposure to various footballing leagues but for the average North American viewer I imagine there's a much gentler easing into the English game. Partly because it's an English speaking league, partly because Britain holds a much greater cultural affinity with most of the target audience compared to the rest of Europe, partly because it has the kindest time difference of all of Europe, partly because the pace and physicality of the game in England is mistaken for entertainment by the people who generally defend the American variety of football to be in some way worthwhile, partly because the sheer amount of money which has exploded into English football over the past two decades helps create this illusion of scale being synonymous with quality. I realise there's a lot of parts to that and some may be more influential/accurate than others, but for whichever ones hold true they're all interconnected and reliant upon one another. The subsequent defensiveness which rises out of this need to latch on to one league and see it as superior becomes a lot more understandable - if not tolerable or excusable - when you consider this.
From a personal diddy-centric view I would hold that the influence of money on warping peoples' perceptions of both English and European football as a whole is particularly concerning this week as
the big clubs try to be bigger again. Aside from this being completely contrary to the whole point of sport it speaks to why English football can be elevated so highly in the minds and hearts of those with no previous vested interest - the illusion of grandeur through wealth and self-exclusion. I think part of the reason for increased interest in the Premier League this season comes from this trend being bucked. While the initial Big Four led to something of a predictability with the league standings (even if the Liverpool to Man City change was largely seamless in terms of their actual relevance to the top end of the table) the fact that more than two teams were actually likely to win the trophy allowed extremely effective marketing to take hold, a process which has grown exponentially since and shows little sign of slowing down. This year, Leicester and Spurs have shown actual credibility in the face of previous dependables becoming completely clueless. The subsequent sense of the underdog being able to achieve something mostly thought of as being impossible because of the money has reignited a lot of dormant interest and created new interest itself. Right now, there's four teams who could realistically win the league. Would it still be perceived as equally interesting if Leicester and Spurs were replaced by Chelsea and Man United? I doubt it. That Leicester have done so with a comparatively meagre budget and with exciting, efficient play and Spurs have done so with some sort of English-centric cohesion for the first time in about forty years adds something else. Even if Leicester are playing in the Champions League next year I doubt their time in these sorts of league positions will last beyond that, Spurs are a more realistic shot to maintain their strength. Still, who do you think values their title challenging more right now? A 50 year old Leicester fan who's seen everything from relegations to multiple cup final losses, never really expecting any success or the 50 year old Man City fan who's seen all that and more but never has to concern themselves with any hint of threat to their relevance anymore given the wealth and infrastructure now in the club? I know which I would prefer, and it's not the option that unbridled, unrelatable wealth would bring.
With all this said, the phrase "The Best League in the World" exists purely as a testament to the strength of the sort of marketing that makes the jaded nonsense above from a diddy who is a neighbour to all of that horror and is directly negatively impacted by it read all the more cynically. Anyone using it without a trace of irony deserves all the ridicule they get and may as well walk around with BARCLAYS TOOK MY TAX MONEY drawn on their forehead.