I just ordered a gallon of Production White to test out. It's pricey compared to Legacy, but I've heard some very promising things.
Definitely share your thoughts after using. That is one of the One Stroke products we have been trying to decide on giving a shot. The problem is they have about 100 different whites and I can't afford 100+ a gallon to try them all!! 
OS Production White is the best poly white I've ever tested to date FOR THE MONEY. I think .357 and Bravo Flex are better inks, but the price is HIGH.
Mimosa, have you tried any of Kevin's whites? His Quick Flash is pretty good for the money, and I think Supreme is also decent.
I'm pretty well set on which white I prefer but I still get offers to test other white inks and there are some that stand out but it seems like the manufacturers are all moving in the same direction and you can essentially get the same ink from different manufacturers due to them making so many different types. Wilflex Quick was good, Sprint ok, Amazing is good, and I could use any of them and get good results.
One thing I'll mention about the NexGen, I did some testing by adding the Magic base to it up to 25% and it only lost about 8-10% of it's opacity with that much added. I understand it may run too short for some auto shops and adding the magic base will help with the squeegee climb without hurting other characteristics. I've tried adding base to other white inks with hit and miss results but most seem to lose opacity at a very high rate once you start getting over 3-4% of a clear additive.
On the discussion of white ink I understand that all shops use them differently and the mesh counts, squeegee blades, off contact, pressure and speed, etc play a huge role in whether or not that ink performs. We print with specific squeegee blades, thin thread mesh, and we print fast so most of the inks mentioned on this thread don't work well for us. However, I can get a damn good print out of most of them if I go backwards (for lack of a better term) with our print parameters. But because we've benefited so much by printing the way we do I prefer to find a white that performs for us when using it the way we want instead of changing the way print to get it to print well.
I still get hung up on price these days even though I realize it shouldn't be in the top 3 of the criteria to look at when buying a white ink. I'd love to be in the $60-65/gallon range but we can literally print hundreds, maybe even 1,000 more shirts per day with a premium white ink versus a dog that was cheap and I hope everyone considers how much more work the shop can get done when using a specific white ink. But if the shop prints the same speed and flashes the same amount of time regardless of the white they are using then I suppose the cheaper inks will perform just as good and you're making a solid business decision if that is the scenario.
