Its not about Germany dominating San Marino, the problem with many internationals is that the games themselves are just dull, particularly World Cup group games and usually most major finals, league football is far more entertaining.
Back in the late 70s I became hooked to the sport through an old one hour show on public broadcasting called "Soccer Made In Germany". Bundesliga at a time when their clubs dominated the UEFA co-efficients. The success of the national team also helped promote the product at a time when foreign players in domestic leagues across Europe were limited to two per club. The show was hosted by Toby Charles, a Welshman who had lived in West Germany since the early 60s. So his knowledge of the German game coupled with his easily understood English language skills made for a popular program for those of us who are now in our 40s and 50s+. When that show went off the air in the mid-late 80s soccer coverage on TV was limited to the Spanish language channel S.I.N. where 'Futbol Internacional' host Tony Tirado would occasionally speak English for the English speaking audience but it was very broken and hard to understand at times. Myself, I turned to shortwave radio where there was basically only one option: BBC World Service because of the common language. This meant learning to follow the English league. Every Saturday there was a very popular program called 'Saturday Special' hosted by the great Paddy Feeny. He was a very entertaining and popular presenter who would read letters from listeners across the world over during halftime and post-match segments. The match broadcasts were simulcasts of domestic BBC productions and I learned the names and voices of great commentating talent like Peter Jones, Bryan Butler, Alan Green, Mike Ingham, John Motson as well as legendary Scottish commentator David Francey and a host of others who have either retired or departed. The English language most certainly played its part back then and I would venture that many international ears that listened to BBC World Service back then continue to follow the Premier League today. They are familiar with the clubs and know the coaches who were players back in those radio listening days. The language barrier prevented other leagues like the Bundesliga and Serie A from establishing such a following the old English First Division had back then. If language can influence followers in the days of radio I would think it could influence television viewers today, albeit to a lesser degree.
This is the sort of topic where it will always be difficult to get consensus. The problem with the question is that there is no agreed criteria which we can all agree that it will be a reflection of the strength of the league. That aside I am certain that we can all agree that this debate is probably an extension of of an ongoing debate of EPL vs. La Liga. We can all agree that in Barcelona and Real Madrid La Liga has the best 2 in the world but does that mean the league itself is better than EPL? Imo one of the indicators of the strength of the league is the number of global superstars in the league. The other indicator will probably be how the stars are spread across teams and this is probably the area where EPL might have an edge imo. I personally feel it is clear to see that the cream of the crop in La Liga are in Barca and Real (Messi, Neymar, Suarez, Iniesta, Mascherano, Pique, Ronaldo, Bale, Benzema, Modric, Pepe, Ramos) and Atletico with Griezman, and maybe Carrasco. This in itself is probably the reason there is so much gap between the two powerhouses and the rest of the league. Yes every now and then there will be a surprise package in the league like this season with Sevilla, and there maybe other tricky teams like Bilbao, Celta Vigo, Malaga, or Valencia depending on the season. On the other hand it can be argued that stars in EPL are spread a little bit better. Chelsea have Hazard, Costa, Willian, etc, Arsenal have Ozil, and Sanchez, ManU( Pogba, Zlatan, Rooney, Mata,) and Liverpool (Coutinho, Mane) ManCity (Aguero, De Bruyne, Gundogan, Nolito, etc). Even the likes of Everton and Spurs have solid squads. This spread means the strength of teams are much closer to each other compared to that in La Liga. It is therefore understandable that the games involving top teams will be less predictable than those involving Barca/Real in La Liga. I did not even mentioned the profile of the coaches or goal keepers. Imo up until recently EPL teams never seemed to take Europa cup seriously but I think this is slowly changing and it will be a reflection of the strength of these leagues in coming years. In terms of organization, administration, marketing, viewership, and other things that makes the league EPL is a better product imo.
The talent is more evenly spread in the Premier League. Manchester United have some great players (De Gea, Pogba, Mkhitaryan). Chelsea have a few great players (Hazard, Costa). Arsenal have a few (Ozil, Sanchez). Liverpool and Tottenham don't have a real star player (apart from maybe Coutinho and Kane), but they have good squads overall with quality in every position. The team closest to the European superpowers is probably Manchester City, who have a handful of players than I consider world class (De Bruyne, Aguero, Silva, Gundogan), and a few borderline world class players (Fernandinho, Bravo, Otamendi, Nolito). However, they still clearly lack quality compared to Real and Barca. This spread of talent in the Premier League is the main reason to why it is more watched than La Liga. Obviously the English language might also be a reason, but the Spanish market is still huge (South America). I just don't find La Liga as exciting. The talent needs to be more spread out. With that being said, we should not underestimate the other La Liga teams. Atletico have reached two CL finals in three years. Sevilla have won the past three Europa League titles. Villareal have a quality team too.
I think historically its pretty close, but also historically there is only one league that has FIVE different clubs that have won the champions league, another example perhaps that the EPL is more competitive top to bottom? At the end of the day it won't make any difference if Real Madrid win the next 20 champions leagues the EPL is a better product overall where it counts - the entertainment game, the matches are usually more entertaining and the competition itself is far more competitive and these are the reasons why people prefer the EPL.