I agree with others, given all the variables, in theory it shouldn't really matter that much. And as others have said, it really matters just as much how gradually it rolls off, vs at which point it is 3dB or 6dB down (a common practice for judging freq response). If it's a ported cab, with a quoted frequency response only down to 80Hz, I would expect it to sound pretty "light in the bass", and maybe better suited to another instrument. If it was a sealed cab I would expect the rolloff to be more gradual, and 80Hz might be fine.
If the 60Hz was ported and the 80Hz sealed they might actually sound pretty similar in terms of perceived bass response. Though the 60Hz cab might have a noticeable bump somewhere above that frequency.
BUT (and this is a big BUT).... I don't think too many bass cab manufacturers are putting out 80Hz specs on their cabs these days. To me the 80Hz rating is an indication that it is not really intended for bass, again especially if it is ported.
The 4k vs 15k shouldn't bother you too much on bass, but your other uses would definitely suffer from the lack of HF response.
Other things being equal, I'd probably go for the 60-4k model for bass use (especially since you play 5 string!) and the the 80-15k model if you are serious about the other uses as well.
Also look into the ported vs sealed aspect. Ported cabs can get really floppy below their resonant frequency which is not necessarily the same as the freq quoted in the response. A high pass filter or a flexible EQ can help avoid this because you can cut the lowest frequencies so that cab doesn't try to reproduce them, you can actually squeeze more bass out of small cab this way.
Lots to consider - playing through them both with your bass would be the next step.
