What I'm using at the moment is ye olde percentile dice, mainly because I'm currently running Mythras, which is BRP family. I'm not really a big fan of "flat" dice curves in general, but I do like the classic BRP skill improvement mechanics (which I'm using, rather than doing it "the Mythras way"), which are only really implemented for percentile. (Although there is a modified d20-based version of the advancement mechanic used in Pendragon, but I particularly dislike d20-based resolution, probably because of its strong association with D&D and, thus, with class-and-level and zero-to-demigod systems.)

As for what I actually *like* in dice mechanics, I seem to be a serious outlier - in most of these kinds of discussions, a lot of people will generally say "I like Dice Mechanic X because the exact probabilities are transparent", but I consider that a bug, not a feature. Pre-4th edition Shadowrun is one of my favorite dice mechanics, mainly for the clear implicit model of complex situations (the number of dice rolled solely reflects your ability, the target number solely reflects the difficulty of the task, and the number of successes solely reflects the quality of the result), but also in part because very few people can look at "8 dice vs. target number 4" and immediately know the exact percentage chance of getting any specific number of successes - but anyone can easily see that, most of the time, you'll get roughly 4 of them. This feels more true-to-life to me, given that, IRL, if I'm shooting at a target on the range, I don't know that I have a 37.48672% chance of a bullseye, but I do know that I'll usually hit within about 5 cm/2 inches of the center. (Made-up numbers, not an actual statement of my personal ability with firearms.)

I also like EABA's "roll some number of d6s, and keep the 3 highest" mechanic, which pushes average results higher with increased skill, but doesn't change the range of possible results as skill levels become arbitrarily high.

And I've lately been really liking what I've read of the dice mechanic in Early Dark, where you roll a handful of d10s (usually 6-8 for starting characters), group them into sets such that the sum of each set is no more than a limit based on your base attributes (usually a limit of 7-8 for starting characters), and then each set is one effect from your attempt with the power of that effect being based on the number of dice in the set. Unfortunately, because there's significant strategy in how you want to group your sets (lots of small sets to create many minor effects vs. big sets for big effects), it's not suitable for solo play, and seems unlikely to work that well for online play either (because, in an opposed roll situation, the other person's dice rolls are hidden information until after you're done grouping them and simultaneously reveal your sets), so I doubt I'll be able to actually play it until the covidpocalypse has passed. But, here again, good luck seeing the percentages in that mechanic without using a calculator.