They didn't really say they liked VOY more than DS9 tho. They were mostly talking about how VOY, despite all its faults and inconsistent writing, still had some really good episodes and wasn't afraid to just have some fun and silly adventures. Hell, even Threshold has shit going for it if you just don't take it seriously at all.
With DS9, I get the impression Mike's issues with it is not the semi-serialised aspect of it or even the overall story, but how the Dominion War developed and how the other big plot points concluded. With the former I feel like he just didn't like the parts that went full SW with their pew pews (which, admittedly, wasn't a lot). With the latter, I absolutely agree that Sisko/Dukat/Winn's storyline was concluded so poorly and lazily it's almost insulting. Sisko apparently didn't have any more issues with being Space Jesus, Dukat became a literal demon who fell down a cliff and Winn, after getting a good dicking from Dukat, ended up getting burned alive (but not before "redeeming" herself at the very last second, I guess). Two our of the three main villains of the show got an ending that was incredibly ridiculous while the Female Founder, as they said in the re:view, got an ending more rooted in real life. DS9 did a lot of things that were unique to the ST franchise, but they also had to nail the ending, which they didn't.