I would propose that neither set being considered really offers specific control over neck tension, so opportunity for one sizer or the other to better dimensionally fit a specific rifle chamber is largely coincidental, and equally, the opportunity for one bullet seating stem or the other to better dimensionally fit a given bullet ogive is also coincidental (notwithstanding intentional purchase of VLD/ELD seating stems vs. standard stems).
Given a standard die, such as these, I'd send my sizer to the OEM to be honed to a slightly tighter neck diameter than I really want for my neck tension, 1-2thou undersized, ditch the expander ball from the sizer, and then use a mandrel expander after FL sizing to get neck tension where I want it. I'm prone to believe neck tension is a bigger knob even than chamber fit, so if I could only have one or the other, I'd rather have proper neck tension than perfect chamber support. So I'd rather have a Lee sizer with honed neck + a mandrel expander, then have a generic sizing die from any brand. Certainly, having both is better than just one, but even a generically sized cartridge has a good chance of presenting the bullet concentrically to the leade without perfect chamber fit, but nothing about chamber shape will improve ignition and primary combustion if we have inappropriate neck tension.
I don't necessarily buy into importance of micrometer seating stems, as they're really only relevant when changing seating depth, which I typically only do once per barrel, with thousands of rounds fired before rebarreling. A standard stem really does the same thing, just without the feedback for adjustment magnitude as the adjustments are being made.
Also, replacing seating stems with those which better fit our given bullet is an easy task, and modifying stems to perfectly fit our bullets is almost just as easy.
So I'd chase neck tension control and bullet fit to the stem, if those boxes haven't yet been checked.
