Is Dilantin still one of the best drugs to treat seizures?

Dilantin. Dilantin is a good medication for seizures. There are newer medications that may have fewer side effects. However, if you have been taking dilantin for years and your seizures are controlled, I am of the opinion "if it a'int broke don't fix it."
No. Phenytoin (Dilantin) is an old drug that can be difficult to dose precisely, has significant drug interactions, can cause toxicity, may cause cerebellar degeneration (this is not definite), and alters calcium and vitamin D metabolism, increasing the risk of osteoporosis. These days I always try to get pts onto a different seizure med unless nothing else works as well or they don't want to change.