My team lost the league by goal difference once to a team full of scout and recommendation players. That was way back (when new features were introduced in the game - bonuses and assistant manager - and also Nordeus made some tweaks that were very significant in the game). My team lost 2-1 at home against that strong team (Andalucia FC) earlier in the season, and later won 2-0 away. It was a season long battle where every match counted. It was my team (tactics) versus Andalucia (quality). Andalucia went to first, then my team, and then later it went to first again by goal difference. I went through hard times during that season. I had to break some habits, which in some way turned me to a better manager. My team had to win by 9 goals or more in the last game to win the title, but only managed to get 6 goals.
This season was a tight one too. see: https://forum.topeleven.com/top-elev...tml#post463790
A few days ago, my team was second, waiting for 1st to slip. 1st finally slipped by getting a draw, and my team went to 1st place by goal difference. After that, I tried to boost my goal difference more by trying to score a lot of goals in the remaining matches. 2nd slipped again with another draw, and now my team is leading with 2 points but still the race is not over. The last game will be decisive.
I had other tight leagues too, but less than the two as said above.