The 7x57 is the only 7mm I would own. My Father used a 7 Remington mag he used it very well and brought down lots of game. I've always been a 30-06 guy because of the versatility of the 30 calibers. The extra 10 - 15 yards point blank range with the mighty 7mm left me unimpressed. Tried a 264 mag, naw, 25-06, I liked that one but it went away. Came to Alaska and my ideas changed. The 30-06 was even more appropriate. But a bit light for some cases, enter the 338 mag, 35 Whelen and 458 mag. If your going to have a thumper, don't be a piker. But the 30-06 got the job most of the time.
243, not need as I already had a 22 LR. But I always wanted a Featherweight Winchester in 7x57 and 6.5 Swede. I have seen what the blister cartridges like the 264 mag, 25-06 would do to meat with the bullets available back then and compared that to more moderate velocity cartridges. I became a fan of the cartridges in the mid 2400 to 2800 fps. In the case of the 30-06 with 180 to 200 grain loafing along at 2600 to 2700 did great work.
With that in mind a 7x57 was on the list, but, never coincided with the jingle in the pocket. The 7x57, 6.5 Swede, 30-06, and 35 Whelen along with a few others fit well in that department.
Advance to the modern times. Lots of great cartridges have been developed. But slow and steady, or should I say moderate and steady get the job done even better when you take into account all of the advantages of the new bullets a person has to choose from. The venerable cartridges I've listed, and some I haven't, do the job without a lot of fluff.
I have to agree with L Ross, the 7x57 is a pretty fine work horse. You can keep all the other 7 millimeters. They won't do anything the 30-06 won't do.