I think I’ve mentioned before that I knit much tighter than I purl. So much so that I use a larger needle for knit rows than purl rows. For these socks, I’m using a 2.75mm needle for right-side rows and a 2.50mm needle for wrong-side rows. This keeps my stockinette looking even. (When I work with interchangeable circular needles, I put different size tips on each end of the cable.)
You might want to try this trick if you find your stockinette has a stripy appearance from the stitches being different sizes on alternate rows.