Well, presumably their own author loves them, which really ought to be enough.
As for what they're comparable to, maybe something like the late Robert Adams' Horseclans series (
Wikipedia)? That one's technically post-apocalyptic sci-fi with thinly-veiled historical do-overs in it, but they seem to have that same sense of plotty political intrigue
cum horse-warriortastic action adventure sequences and (re)building a civilization under a charismatic leader, at least as far as I can tell from reputation and the one Horseclans book I got from Fictionwise way back when, and a vague memory of having actually bought (but not yet having gotten around to reading) these exact books from eBooksDirect a couple of years ago.