Really? No other opinions from a group like this?
I just saw this thread!
IMO, an ash/maple J with single coils in 60's position, with a nice 2 band pre (with passive bypass) with passive tone control covers the most ground of any J spec I've owned or played.
My logic is the following:
1) It is always easier to dial brightness and grind out with the passive tone control than to try to muscle it in with EQ on a darker voiced bass. Hence, I can get closer to an alder/RW tone with an ash/maple bass than the other way around.
2) Single coil pickups have (typically) a more midrange voicing which can be key in a mix, but still have plenty of sparkle up top if you need it.
3) The 60's spacing with ash/maple gets you 85% to what many call a 70's tone (plenty of brightness and grind for a good slap tone), but that 60's pickup position at the bridge allows you to get a fat, burpy tone when favoring the bridge pickup or really digging in close to the bridge.
If I was allowed to own only one bass, that would be the spec I'd choose (and is the spec of my Sadowsky NYC ash/maple bass). Of course, I also own two other J's, both quite 'vintage legitimate', one 60's alder/RW, and one 70's ash/maple. Between those three... I have everything possible covered in the 'J world'.
IMO.
Edit: For those who don't need quite the upper mid grind, and/or like the look of a darker fretboard, Morado/ash is also a very good combination, and sounds very similar to maple/ash.