The spell my party is most afraid of is Power Word Kill, because it snuffs anyone without d10 hit dice AND at least a +4 con save without any save or protection at all, and Counterspell on it will absolutely save someone's neck. The spell they're second most afraid of is a well placed Prismatic Wall, which Counterspell will also knock down. So I think either you need to revisit your thinking there or we have very, very different parties.
Different parties I guess. PWK doesn't even work on high-level PCs* unless they are wounded (so can't be used from ambush), and it has a short 60' range, and even if it does work a single (possibly-quickened) Revivify reverses it. And it's hard-countered by Death Ward, which should be SOP for high-level parties in risky situations.
Prismatic Wall: just wait it out, behind your own little Wall of Force if necessary. It no longer lasts from three hours like in AD&D, it's only ten minutes.
I fully appreciate the value of Counterspell, especially on Lore Bards (Peerless Skill + Jack of All Trades = 81% success rate on 9th level spells) and to a lesser extent Abjurors (Improved Abjuration = 65% success rate on 9th level spells) as opposed to a normal wizard (35% success rate on 9th level spells). But I see it as more of a defense-in-depth thing Just In Case someone tries to mess you up with the wrong spell at the wrong time, rather than a hard counter that you'd want to rely on intentionally, because it does have pretty serious limitations. Remember that a 3rd level Counterspell is still more vulnerable to Counterspelling than a 9th level Counterspell, so if you really, really couldn't afford a PWK right now you might be better off just burning your own 9th level slot instead of a 3rd level slot. There's a time to economize and a time to spend. Also, Greater Invisibility makes you immune to Counterspelling unless your enemy has See Invisible up. Even just a plain good Stealth roll can result in a non-Counterspellable spell.
TL;DR being able to Counterspell 9th level spells with 3rd level slots is fun, but a genuine archmage has plenty of ways to bypass Counterspell.
* At 11th level, the Necrolock in my test party has 81 HP + 16 temp HP. The Paladorc has 4th level spell slots (P7S4) so can cast Aid IV (no concentration, 8 hours), which would give the Necrolock 96 HP. That means the Necrolock, at level 11, is only 4 HP away from being immune to surprise PWK if Aid IV becomes SOP. (Right now it's not SOP but if my players were as scared of PWK as yours are you can bet it would become SOP pretty quick.) He has an unusually-high Con, but even with an low wizard Con (12 is low for a wizard) he'd still reach 100 HP by 15th level. (79 HP + Aid VI = 104 HP.)