I would say that KPNT and 91X (XTRA) probably have the best fingers on the pulse on what alternative listeners like right now - or at least appeal to the broadest range of them. Both KPNT and XTRA touch alternative metal veterans like Chevelle, Deftones, and Tool (KPNT also likes to pick up newer acts that fit that label, and they give the red carpet to post-grunge legends Shinedown still) - but their bread and butter are a wide variety of indie rock. They do add some pop-punk revival artists without going overkill on the movement like Audacy does. They also pick up a smidgen of indie pop, but indie pop tends to be used like parsley on a really elaborate dish on both stations I would say.
They both also respect heritage alternative acts and will bring out Depeche Mode, INXS, Tears for Fears, Siouxsie & The Banshees, etc. along with the beloved 90's fare and a decent amount of 00's acts. 2010s hits do appear on both stations as well - usually one or two of those per hour.
I think part of why KPNT and 91X continue to have success is because they keep their veteran listeners happy but also continue to bring in new listeners in by picking up the hot new things that still fit their images. KPNT's last 6+ was an 8.3 - and while that doesn't tell the full story I highly doubt that all of those listeners are 25+ when the number is that high.
91X's ratings aren't as stellar as KPNT's - but they've been good enough to be almost double (or outright double) their Audacy rival KBZT. There was a period when 91X was absolutely struggling against KBZT, but the regional consolidation policy absolutely killed their rival and brought 91X's ratings up due to listener migration.