Best Email Verifying Tools?

I have always used Neverbounce to verify all email addresses (which come from Apollo 90% of the time), but am not convinced that it actually works well. Its common for Neverbounce to take out 30-50% of the emails I pull from Apollo (all of which Apollo says are already verified), but even with the much smaller list left over, many addresses still bounce for a number of reasons.

Anyone else have a similar experience? Opinions on competitors vs Neverbounce?