League position is mostly based on luck, It's all about what tasks you get assigned, and having the time and resources to complete them.
In the 4th league (City), you have an 8 in 100 chance of winning Platinum keys. Given the fact that it's mostly luck of getting top8, on average you might have to do the league 12 times (1 in 12 chance) which is 12 weeks, just to win 1, 3 or 5 Platinum keys, and that's only once you reach the 4th league.
I'm personally not going to torment myself for such rubbish rewards. I'm boycotting League until something gets done about it, and I strongly advise everyone else to follow suit so they hear us loud and clear.
I'm not happy about coming 61st and being 33% short of placing in the top10. I know I put in just as much time and effort as everyone else did, and yet only a select few were lucky enough to get get promoted or get a reward (I got nothing, not even 1 token or simoleon).
I put the entire game on hold for 5 days for the League, plus a lot of pre-planning prior to the contest start. If I didn't do the League, I would have made 500,000 simoleons selling in Trade HQ, plus plenty of keys/items from airport/cargo (however I don't do that, I have so many already). I don't even have much use for simoleons other than completing more epic projects, but I already have 60. So what's left for me? Platinum keys. But there's such a slim chance and so much luck involved just to win 1.