Tincati is also one other brand that is first tier. The ones I've seen and owned have been made by Kiton, Attolini, D'Avenza, I think St. Andrews too.
My Attolini x Tincati is 100% identical to the same model by Cesare Attolini house brand, and both are priced almost identically too.
Paul Stuart - Stuart's Choice is/has been made by Isaia, St. Andrews. Excellent stuff, but a bit expensive brand new, considering that you could go to the brands (Isaia, SA) directly and save some cash.
I've owned a truckload of St. Andrews, and the quality has been consistently very good. But with that said, what you pay varies A LOT. My experience is honestly that you get the same St. Andrews suit, whether you pay $3K under brand X, or $5K under brand Y. Same goes for Belvest.