If it's just raw brightness you're interested in, you can actually look up the photometrics. A Cantata 18/32, when new, provided 1190 Lux. (Source) An ETC Colorsource V with a 15-30 zoom lens provides between 1518 and 484 lux, depending on zoom. (Source).
The Cantata doesn't say what zoom level it was measured at so I would assume that figure is for it at it's narrowest. They seem broadly comparable, and I would assume your Cantatas are not performing at their prime any more anyway. Colorsource V is about 200W, so you're probably looking for fixtures in the 150-200W range.
BUT: Additive colour mixing, in saturated colours, is going to be much brighter than the subtractive colour (gel) for the Cantatas, so depending on how you're using them, you may be able to err lower.
Having looked at the options, I've found that ETC's stuff is actually pretty price competitive at this level of product. There are cheaper fixtures but they're way worse, and there are worthy competitors, but they are almost the same price IME. Matching a 1.2K is actually pretty hard work, so you need something fairly good. The Prolights stuff is reasonable and might be worth looking at: https://www.prolights.it/product/ECLFS. They don't seem to have Photometrics for their Zoom lenses, but their figures for fixed lenses are very respectable. (But, obviously, that's to be expected - you'll get better performance from a fixed lens.). The Chauvet E2FC is also in the ballpark and a nice fixture, but not as cheap as you might hope.
And caveat: Manufacturers can be pretty naughty when measuring and declaring their photometrics, especially at the low end. Do get a real-world demo before pulling the trigger...