Given the choices availaible in a vacumn, I would prefer:
1. HexLOS
2. CircleLOS with psudo-euclidean movement and ranges
3. SquareLOS
4. CircleLOS with psudo-euclidian ranges, and Chebyshev movement (what we have now)
1. Is hard to implement in ascii, (You need to use two offset characters to represent each hex) and would require more drastic changes in crawl (pretty much all the vaults would need to be tossed, and a lot of the graphics would need to be redone, map generation would need to be rewritten, combat AI would change drastically etc. etc.)
2. is hard to explain (It takes more time to move diagonally than horizontally, because you're moving further, this can get you killed if you aren't paying attention) and is harder to do (because how do you define 'adjacent' for melee ranges? It gets ugly and weird) and probably doesn't fit well in crawl (You'd pretty much end up with all new mechanics, since you'd have to impose some sort of range-based mechanic on diagonal melee, which would be weird and hard to balance)
So I guess I consider 3. to be an upgrade, but I consider it a *very small* upgrade to the "is more consistent" department. But I actually have fun, personally, manipulating the different ways you can handle diagonals, I realize it's inconsistent and weird, and there's various circumstances where being aware of the topology can result in optimal movement being strange and nonintuitive, but in some ways I like it that way.
If we do move to SquareLOS, I'll be a little sad, not because it makes the game objectively worse in any way (I think it makes the game objectively better), but because we'd be losing one of the weird quirky elements of the game, and I like weird quirky things.
/Offtopic/
So a long while ago I played this PS2 game called 'SSX' (it's a snowboarding racing game) and the first one was clunky, and a little awkward, but still a lot of fun.
The second one (SSX2 "Tricky") they cleaned up the mechanics a LOT it's much cleaner the interface works better, but there's still some clunk in there, different characters don't always perform quite as you'd expect in comparison, and different board types don't perform as well for different things, which means that you have to play *differently* depending on what you pick (And in some cases are limited in what you can do, one character might not rotate as much as another for example), there's also weird spots where you can kind of break the game here and there (you can break out of the map where they didn't intend you to).
With SSX3, they cleaned up the interface to the point where everything is crisp, all the characters behave exactly the same given the same stats, and all the boards perform tricks in the same way, if you go off a jump at a certain speed, you can be sure of doing just so much rotation with a given amount of stats and can land the same trick with any character, and there is absolutely no "breaking" it.
Naturally the 'smooth, clean, quirk-free' version is actually the least fun for me, I can intellectually recognize it as superior, but I just lose interest much more quickly.
This reminds me a little bit of that.