Good question really, personally I would say on the shooter installed magwells that the difference between Chen and Wilson BP or whomever is smaller and really a matter of personal preference.
On the Chen gunsmith fitted and welded magwell I don't know who else offers a similar option and I can say that the welded Chen magwells that I have on several guns I find are the best in terms of slightly reducing the size and therefore printing, fit and finish & of course function. A number of the tier one smiths now swear by them, take that for what it is worth. For me as a guy who likes having a magwell on my guns I don't know that I would do a build without a chen welded on magwell now.