The Tavern

This concerns rings of strength/intelligence/dexterity/protection/evasion and amulets of reflection.

When wearing plain jewellery with a random bonus: upon finding find another one of the same type, optimal gameplay would be to check if it has a better bonus, which is kind of tedious for the chance of only a few improvement points.

My proposal is to set all these to a fixed value (+5?), so there is no need to e.g. try on more STR rings if you're already wearing all the STR rings you want to wear. This also means you stop auto picking up STR rings after finding 2/8 (uncursed) ones.
Artefacts would be unaffected and still get random values.

To keep up the annoyance level, cursed jewellery could generate with a negative bonus.

I think that a similar result would be reached, if identifying the item type (ring of str) caused all the numbers of this kind of item to become immediately visible (+3). Sure, you wouldn't put on cursed rings, unless the first ring of that kind that you find is cursed, but I think that, by the time you find your second ring of str, you probably already have enough scrolls of remove curse to make curses effectively irrelevant.

We could also split "negative stat" from "positive stat": Ring of stupidity, clumsiness, and weakness. That way, the tedium of trying on every ring (and twiddling your autopickup) would go away, but there's still a risk to trying on rings. Practically, the difference is going to be miniscule, but it would leave the risk of trying on unidentified rings. (Even increase it slightly, I suppose.)

Worth noting is that hellcrawl has a version of this: stat rings (str/dex/int) are always +5, and protection/evasion rings are usually +3, but it is possible to find +6 versions more rarely. Imho that's a pretty good system; prot/evasion are worth wearing at +3, and +6 are very powerful. Keeping them in the game is cool, but they are appropriately rare.

I'm not 100% sure but I think slaying is the same at +3, but I've never actually found a +6 slaying ring, they may not exist.