Great topic! I think that a well made harmonica style reed melodica plays very well. I have long been a fan of my older model Hohner Piano 36, it has harmonica reed but is still a very good instrument. I also like quite a few of the older suzuki and hohner models that all have harmonica reeds.
At the same time I only have experience of one accordian style reeded melodica, my Hohner Professional 36. It truly is a wonderful instrument with a different sound. It’s harder to play and requires more air than any of my other melodicas, not an impossibly large amount of air but it is a noticeably higher air requirement. I note that i refer to accordion ‘style’ reeds rather than just saying that they are accordion reeds, having an accordion repairer match an accordion reed to my Professional 36, it was obvious that there is a lot of difference between those in the pro 36 and the accordion reeds.
I had thought, as I am far from a competent keyboard player, that it might have something to do with the ability of the musician who plays the two different types. It would seem certainly that amongst the more accomplished keyboard players and professional musicians on this forum, that it might come down to a personal preference and the style of music being played. Personally, I don’t have a preference, however I do get a lot of enjoyment from repairing the older models and making them playable again, while I will always have a reliable newer model to just pick up and play around with.