What is the best treatment for onychomycosis?

Several treatments. The reason you hear so many different treatments for toenail fungus is because there is no perfect, sure-fire treatment that works 100% of the time. I've seen vaporub work, as well as other natural oil remedies, but very rarely. You can also try laser therapy, antifungal creams, paints, or even oral medications if your doctor deems you healthy enough to take them.
Oral terbinafine. This is also sold as brand "lamisil". That costs 100x and is no better. The generic is sold by prescription at walmart for $10 cash for 90 days. This is more than usually needed. The topicals are not effective for nail fungus. Laser treatment costs $1000. Which is not covered by insurance and you still need several months to see results.
A lot to consider. Consideration must be given to various factors, including but not limited to, the age and health of the patient, as well as a host of others. The severity, number of toes involved and length of infection are also important. In early onset infections, a topical might work well and be the safest. The more heavily infected may need the power of oral medications like oleterbinafine or itraconazole.
BEST? I think the best is an oral medication. Terbinafine is probably the most popular. Talk to your dr. about side effects and drug interactions.