I don't believe the spring "brand" makes the most difference, either they are Wirth, Hagon, Progressive or whatever brand.
First and foremost, the spring rate needs to be suitable for the bike/ rider/ luggage/ skill/ type of riding combination.
Then the preload needs to be set to achieve a reasonable laden sag.
To me, that ends up with a suspension supplier that is able to offer a wide selection of spring rates for the requirements. That would be RaceTech, Øhlins for some bikes, various British suspension companies etc.
So to me, 100 or 200 dollars more spent on a carefully selected spring, and emulators, is a much better deal than buying any random "progressive" spring from a supplier that offers only one spring option for any model.
Buy cheap and buy twice, basically.....
(I fell in that trap when I got Hagon shocks for my XS.
FYI, the shocks were the "correct" model for XS650, but I just couldn't live with them. So sold them for half of what I paid, and got a pair of Øhlins. Bingo!)