Provided the kit is well within date there's usually nowt wrong with most kit yeasts imo (or certainly the ones I have done) and so I never replace them, can't see the point. The exception seems to be Muntons Wherry and Sundew which do require substitution
The issue is the quantity of yeast, not the quality. Wherry and Sundew both come with small packets of yeast, 7g vs 11g which is the standard yeast packet size. The yeast itself is actually rather good if used to make up a smaller brew 10-11L. I've just done single-can brews of both to 10L and the yeast has fermented them out fine. It's just a bit risky to use that small a packet for 23L. Muntons must know the issue because with kits they've produced later, such as Cwtch, they include 2 x 7g packets.
I'm also a fan of Wilko yeast, it's my go-to yeast, meant to be re-packed Nottingham and is particularly good for English ales, stick well to the bottom of bottles