Either is fine. This is a common question related to the present perfect, and isn't specific to "I've never met". For example:
I've always thought that funny people were/are smart.
I would say that the past tense is more common with "I've never met", since you're referring to people you have met in the past -- but this contrasts with the way English speakers like to use the present tense to talk about people who are still alive.
Most funny people I've known are also pretty smart.
Which is to say, the past tense slightly implies they might not still be alive. For example:
The men in my family always were at risk for heart disease.
In this sentence there's a subtle nuance that some of these men died from heart-related ailments. If I want to avoid this implication, I could say:
The men in my family are at risk for heart disease.
Still, don't overthink it. Sometimes people say things to convey subtle meanings. Sometimes people say what's most common without thinking too deeply about it.
I've never met an English student who wasn't frequently confused by all these seemingly contradictory language "rules".