I'd second the Reaper recommendation. Despite the 'experimental' tag I found Reaper works great out of the box on Debian, Ubuntu and IIRC Mint as well.
They also state that Reaper runs well under WINE, but I personally found no need for that as the native Linux build 'just worked'. The trial version is fully-functional if you decide to take it for a spin.
That said, I've yet to try Ardour so I'm not comparing the two.