I'm no expert in politics, but probably democracy works better in places with higher average education levels. My intuition is that, other than education levels, or maybe even despite them, the main factor determining whether democracy works in a given location is how well it can be set up effectively / transitioned from their current system in that location. So in other words the differences have more to do with the process of creating democracy (where anything can go wrong) and its results than differences that would apply if every location's democracy were somehow equal in construction. But I know very little about this stuff.

I don't know what's better between meritocracy and mob rule, but I think the problem with meritocracy is how to ensure that the line of meritorious people appointing further meritorious people doesn't get corrupted somewhere along the way. Probably there are ways to set up the system that mitigate corruption, but the best ways would probably only delay the inevitable until further into the future. The problem with mob rule, on the other hand, is that the common person is too ignorant to make a lot of important decisions for the state. As was pointed out in one of the comment threads, we sort of have a meritocracy through mob rule in that it's not a direct democracy but rather a democratic republic, but on the other hand, the merit of the people appointed is only as good as the intellects of the people voting. And besides being relatively dumb and uneducated in how to run a country, the people are easily manipulated by politicians who will say anything just to gain power and will do anything for money, and also by the media which (in a capitalistic country) is sensationalistic and owned by the rich who have their own skewed political interests.