Boy, you guys aren't pulling any punches on cartridges even taking shots at my all time favorite the .25-06 Remington. For hunting purposes I've found it hard to beat. It is the hardest hitting varmint cartridge I've ever seen when loaded with bullets weighing 85 to 90 gr. Load it with heavy bullets and your good for larger game. Really a dual purpose cartridge. The only handicap this cartridge has is bullets. But even that is changing as Berger makes a real sweet 115 gr with a fairly decent BC in .257.
That said I'll venture to say I despise any cartridge under .224 caliber, they are just to finicky. I once owned a .17 Remington. That cartridge could shoot 1" groups one day and 3" groups the next depending on temperature, humidity and wind. I gave up on the .17 and never looked back. Never tried a .204 and won't because of my experience with the .17.
Another that I think is nasty is the .223. I carried one while in the service and it worked great for what it was intended to do which was shoot a man at 300 meters. But as a varmint cartridge it's a crap shoot for anything over 200 yards. Still, it was always nice to have one at the range while waiting for a barrel to cool, and it shot excellent groups at 100 yards.
Also owned a 7mm Rem Mag. It was a decent cartridge but I also had a rifle chambered in .300 H&H mag that was just more versatile and seemed easier on felt recoil. I've come to the conclusion that the .300 H&H Mag is a real gem, only falling out of favor because it needs a magnum length action. I still have the H&H mag.
One that I never liked is the .308 Win. Never saw a use for this cartridge till I got one in a Winchester Stealth, one of the last to leave the old factory. It changed my mind big time and I'm a .308 fan now.
Never owned a .270 and always wanted one. But it's to close to a .25-06 in ballistics so I passed over it.
I think it comes down to the cartridge and intended use more so then just the cartridge it self.