It depends. Do you want to do both 50/50? Then a traditional CNP fellowship would suffice, and would make you decent at both, but not stellar at either. Honestly this is more than enough for private or privademics.
Do you like EMG more? Then do a CNP-EMG or a neuromuscular fellowship. Same goes for epilepsy. The caveat is that now neuromuscular and epilepsy fellowships are starting to encroach into 2 years of training, and the second year is mostly research filler as I understand. I did CNP-EEG and took the epilepsy boards (this pathway is now closed, btw). I will also say with epilepsy the second year makes a difference IF you want to do surgical epilepsy I.E. take people for temporal lobectomies, hippocampectomies, laser ablation, RNS, etc. That I think requires a bit more finesse.
Hope it helps.