Hard core, at least a newer one from mid 90s and up. Stay away from older hard core balers like the Hesston 5510s and JD 510s. They had narrow throats that wouldn't let them pick up quickly and made it hard to start a bale.
About the only advantage that a soft core baler has is price. For a baler from the same year, you'll spend less money on the softcore. But as I mentioned in my other post about the Bad Idea baler, you can find the smaller hard core balers that give you the same weight as a larger softcore baler for about the same dollars.
Hard core balers delivery better consistency, faster pickup speed, better resale, the same maintenance requirements and the same ease of use as a softcore. I should mention that a hard core baler MAY not bale ultra dry straw, and you'd have to wait until night to do it. Having said that, I've never had an issue myself. I have yet to move into a field that my NH 664 won`t bale.
Rod