Which has less side-effects, especially tiredness or edginess ?

I am currently taking Mysoline (Primidone): 250 mg, 3x/day ... reduced from 300 mg, 3x/day, due to the Primidone level in my blood being too high... approx.16.
After a few months, at the current dose, the level is roughly 13.5. Medications for other non-neurological problems may be interacting with it... increasing its level in the blood. My neurologist asked me to review Briviact online so we could discuss possibly switching meds. She feels that Primidone has more side-effects than Briviact and that it is most likely responsible for my extreme tiredness. I feel it is a combination of this and cardiac-related meds that I must take to control my BP/HR.
A stent was inserted into my heart's LAD artery last year.