They were both comic relief. The Doctor was better because his character was a deeper, more developed character that viewers cared more about, so the humorous situations he was placed in had more depth and situational resonance.
Neelix was a sight-gag first and a character second. For an actor, that’s a lot to work around. Certainly, Phillips was the guy for the job, and he had his spotlight moments in the series, but he was only really an endearing character sometimes and mostly at the end of VOY’s run. How his character was painted in the first three seasons made it really hard to like him at all. The writers eventually did his character right, but he’ll never be as beloved as other characters, especially the Doctor.
Edit: Phillips, on the other hand, has earned his place as ST royalty.