Red stripe. As for my reasons, some of this you may know already, since you've read other Peavey threads, but here goes...
My principal reason is that a red stripe is going to be newer, and therefore should have less age/wear on the circuitry. Electrolytic capacitors can need replacing over time. Yes, Peaveys are made to give years and years of trouble-free service, but as they get longer in the tooth they can develop issues.
A teal stripe amp will be somewhere around 17-24 years old. A red stripe could be as new as 5 years old, and no more than 12 years old. So if I were in your place, and I could go with either for the same price, I'd go with the red stripe.
I have bought and will continue to buy used Peavey teal stripe and TransTube amps. Personally, I'm hoping to snag a USA made red stripe Bandit. You can tell the MIA models, they say "Designed and Made in U.S.A." right on the front. Also they typically (though not necessarily always) have the block letter "Peavey" logo, as opposed to the "pointy" logo. The ones made in China (2004-2007) have the pointy logo and read "Designed in the USA." I prefer MiM (Made in Mississippi
) amps, but I'd take a Chinese one if the price was right.
The teal stripes are good amps. I have one left in my collection, an Envoy 110 teal stripe. Not a lot of clean headroom, but a nice amp. I still use it sometimes for practice at home. I had a teal stripe Studio Pro 110, an even better amp. I wish I still had one; I gave mine to my son (still get to play through it every now and again). I have a Studio Pro 112, the model that came after the teal stripe, a black box/silver stripe amp, the first generation of amps labeled "TransTube." Very near to the tone of a Bandit, IMHO, 65 watts, and about 9 lbs. lighter than a Bandit. I took it to a jam a week ago; Volume was set at 11 o'clock, nice and loud and clean. It held its own with two other guitarists going through the PA and a loud drummer.
I think I'd recommend you go with a Bandit. That sitting in with a jazz big band thing sounds like you might need plenty of power on tap. The Studio Pro or the Express might do (no experience with the latter, though I think they're comparable to a Studio Pro?), but the Bandit will probably best serve your needs for jams and gigs. And again, red stripe. Newer, and more features to allow you to tweak or attenuate your sound.