You know it's not an either/or proposition, right? You can still use reddit even if you also have an account at the competitor.
But anyway: if you are someone that only cares about looking at whatever BigCorp allows you to look, then sure, keep using reddit.
If you'd like to have some form of control over the content you value, create and would like to promote, then your best bet is to fight for alternatives to the current big centralized systems.
