Not a bunch of experence with the 8mm,
But you have other rifles for the bigger game. The 7mm is perfectly suited to many purposes. I push 140 grain bullets out to 2900 with my Ruger #1. And have plans to build a bolt action riflr for the cartridge , if i can't buy one I like.
The 8 is clearly a fine round, and for bigger game it would be my preference, but the 7 will drop any mule deer as quick as any other cartridge.
And with all the different bullets available , its a fine choice...tj3006

Either is a fine cartridge. I can't see how you could make a bad choice with either.

The 7x57 I feel has the edge if you plan on shooting bullets on the lighter end of the spectrum and the 8x57 the edge on the opposite side. For what its worth, to date, a 185 grain bullet does all I need in the 8x57.

With elk and moose being primary targets, my choice would be the 8x57 because of its ability to handle heavier bullets. Lou

Its hard to say no to the idea of a light 7x57,
yet if I found myself regularly loading heavier bullets[150gn+ range, with idea to hunting larger species than deer], Id go 8x57 loaded with pills like; http://www.gsgroup.co.za/323160HV102.html ..approaching 3000mv.

But if one prefers lighter recoil, have no fear, 7mm 120gn monos are well proven to penetrate and cause wound channels as much as heavier cupcores up to 175gn.
As much as I adore 7x57, If I was permitted only one rifle for a variety of game in different environments, it would be 8x57 over 7mmauser.

i'd suggest the 8x57 since your also hunting the bigger stuff.

8x57 would be my choice for what you want to do. You may want to find a Husqvarna built M98. I have one w/ Express sights and a quick detach side mount scope that is perfect for what you are looking for. I like the Sierra 175gr for most hunting. Great bullet. I use 150 and 200gr also depending on game, but the 175 always seems to get it done very well.

I like both rounds, but I prefer the 8x57 and I'm currently looking to build or buy a 9x57. It's been my experience that the bigger bullets at moderate velocities tote more deadness to critters.

I've had really great results with the 200 gr accubond on deer over the past several seasons, but this year I am going to load up some 185gr remington CL's. They have an outstanding reputation in the 8x57 and a couple of my friends have reported same.

Good shooting
Weagle

I can see a trio of '57's; a 7, 8, and 9.. They'd cover the waterfront here.

I love the 7x57 and hunt with it more than any caliber for game up to elk/kudu. I don't need to say anything else, as my walls are full of game shot with the old 7x57 and either 140 TSX or 160 NP bullets.