i call the quality 'present'.
I play primarily spruce top ukes. I have a Soprano, a concert (sorta) two tenors and a Baritone with a spruce top and for me it is the chime- they ring like a bell and sustain for days. Bright as they can be. The part of the equation that is missing is the bark you get from Mahog or cedar.
I generally prefer Mahogany. But after seeing Benny Chong (Thanks Dan!) (http://youtu.be/VDugM9aaSlo) playing his solid spruce-top koa sides baritone custom Kamaka I have been yearning for a spruce top barry and yearning bad. I have an inexpensive Regal that's nice, but am starting to add some better modern Barry Tones to my fleet to compliment the vintage, on days when I'm not in the mood to nurse friction tuners, haha!
So, someday a regular Kamaka baritone, but next is a spruce top. Kala makes one--but I haven't been that impressed with intonation in the videos. That's always hard to judge cause it could be just strings settling--but then again, it could be the uke several cents off as it moves up the fret board. But their spruce tops are pretty, and I love my Kala Ka B, so maybe.
Also have my eye on this: http://www.theukulelesite.com/pono-rbc-rosewood-baritone-cutaway-spruce-top.html
Would love to hear from baritone players who have spruce top instruments.
When I still thought I'd be getting a Mya-Moe (financial restraints make that unlikely now) I was pretty much settled on Koa back and sides with a Spruce top. From the samples I've seen and heard I thought this would give me the "right" balance of warmth and brightness for how I like a uke to sound.
When I aimed a bit lower price-wise I started looking for ukes in the $500-$700 range that had spruce tops as well. I really need to find my way to a store with a large and varied ukulele selection to play and hear a bunch of different ukes (and I will do this before I buy) but there is nothing remotely close to me here in mid-Vermont like that.