I believe wot is the solution, and global state/metrics/algos have limited future. We don't use 'number of links' to measure the popularity of a website. We don't really even have a concept of such a metric on the web (that normal people would understand), that should tell us something.

That said, the only hard-to-game metric that worked reliably at huge scale is pagerank. But it's costly to calc, and thus only a few would run it, and results depend on the inputs which will differ, and so competing ranks would always differ, even if they were based on the same algo. And then it's just a meaningless number to most people, only usable for algos. 

Also there's a difference btw knowing how many people follow you (you know whether you cheated or not), and how many people follow others (when you want to compare yourself just for fun), and a reliable metric usable for algos.

In short: follower count of yours is a fine metric most of the time (to estimate how many people might hear you), follower count of others to compare to yours can be manipulated but that's unlikely and harmless, follower count for algos is a very very bad idea - pagerank for global, wot for personalized.