Lithium is still the fallback drug of choice with the best track record. In some countries it's as much as 50% of patients.

I was first put on lamotrogine and it's mental side effects were far more debilitating than lithium's physical side effects. Lamotrogine destroyed my working memory to the point I'd consistently leave food on the stove and just forget about it. Lithium also works better for me. It is also dirt cheap compared to alternatives which don't work as well for many people.

Other forms of Lithium also have potential for future treatments, with Lithium Orotate being considered for trials recently (few side effects, safer, crosses blood brain barrier more effectively, but was mischaracterized in the 70s and largely ignored until now).