Jon between 1990 and 1993. That man was THE frontman, no one could touch him vocally.
I like Jon's 80s period and also all the way up until pretty much Crush.

Overall though, Richie has the better range no question. Also his vocal stamp is very distinctive. Something that can't be said about Jon.

As about one single vocal performances, Jon wins live - that Blaze of Glory at the Oscars could make mountain's crumble.

In the studio, Richie's version of When a Blind Man Cries is the most intense vocal performance delivered by anyone in the Jovi camp.

I do agree with Javier though. Richie lacks vocal discipline, technique and control. He used to have them on the guitar but seems to have lost them too. Now he sings like he plays, all over the place.

Even so, it's a bit of an unfair comparison. Jon is a trained vocalist. Richie is a trained guitarist. Yes, they do both, but it surely wouldn't be fair to make a comparison the other way around.