Sorry but I have to disagree here. I still think that Voyager had the best characters even if I do hold the characters you mention in high esteem.
I can agree that Chakotay's background was poorly researched. But the character was great and imagine what could have been with good writers who had done a better research and wrote better stories.
The same for Harry Kim who had potential but was sadly wasted. Read some of the early Voyager books where Kim is actually doing something and you'll see the difference.
And Neelix is actually one of the best Star Trek characters when it comes to depth and realism.
Just consider his tragic background. He was living a happy life with his family on Rinax. All of a sudden all that changed when his family and friends were killed by the Haakonian Metreon Cascade. Now, that could have made anyone lose his or her mind and that happened to Neelix. In fact, he was actually a drug addict for a while but his friend Wixiban helped him out of this (Voyager book "Pathways by Jeri Taylor).
Then he found a new home on Voyager and did all he could to fit in. OK, he definitely had his issues. His annoying jealousy when it came to Kes (which lead to him losing her in the long run), his whims about being Morale Officer, journalist and whatsoever but that was obviously a result of the trauma he had went through. In that way, he was actually more realistic than some of the casual Starfleet cut-out characters who go through life without a scratch.
Not to mention that despite his inner demons, sometimes annoying behavior and despite his exaggerated ways of trying to please, he actually did everything he could to be friendly, helpful and supporing to everyone and as I see it, that makes him admirable in many ways.
"And little Sir Neelix in his colorful clothes
and the Anthraxic Citrus Peel Orange Juice in his glass
And Little Sir Neelix with his Leola Root plate
proved the strongest man at last
Without him, the crew would never have got so much food
without having to steal and loot
And Janeway would never have got the strength to lead the crew
without the little Leola Root"
Last verse from the old English song "John Barleycorn"
Song recorded by Traffic in 1970
and lyrics slightly altered by Lynx 2021