If you had to choose between these three for mule deer, which would it be? 7mm.Rem.Mag, 257 Wby Mag. and 25-06. I know that there are plenty others out there that will work, just curious about these three.

Which ever one I shot the best as they are all excellent choices for Mule Deer.

IMHO, 7Mag is more than is needed for any deer, and the .25-06 or .257WM would be better suited. In fact, I think the .25-06 would be ideal for mule deer. BTW, that's what I use as my mulie gun

ALL OF THE ABOVE WOULD DO!
I'd say the 25-06 Fast, hard hitting and easy to shoot, but if one of either the other two is a better shooter well then there is your answer

Just my 2 cents.

I think the 7mm Rem Mag is the best choice because where you find muleys you often find a lot of wind and a good 160 gr. 7mm bullet bucks the wind better than anything you can shoot with the other two you mentioned.

I'd probably go with the 7mm mag.

I used to be a .25 fan. I lost a good buck well hit with a .25-'06. I found the carcass a few days later still intact enough to determine entry/exit points. It should have been DRT, or within 40-50 yards anyway, it should not have gone full-steam over a ridge 400 yards away. I lost a lot of confidence in the smaller calibers right there.

Tom

...A beautifully flat shooting 7mm that can be rolled up into a lighter easy carry rifle than required by the 7mm Rem Mag is the Winchester 284. The compact and efficient 284 hits with authority and shoots as flat as the 270 Winchester.

It would depend on the rifles involved and, more important, how I was hunting them.
I've got a 6 lb., 14 oz. .25-284 which is ideal for back pack and rough, open country hunting done on foot. A 7mm Mag in such a light rifle wouldn't be a good choice for me. Kicks too hard, etc.
For a guy that packs a heavy rilfe, say 9-10.5 lbs., doesn't walk very far, and has lots of long range shooting under his belt, a 7mm magnum has it's adavantages. Bucks wind better, hits harder at the longest ranges, etc.
The .257 Weatherby is kind of a special case. Nothing shoots flatter. Recoils considerably less than the 7mm mags. E

All 3 of the rounds you mention will do you just fine. For me, it would be about which rifle they were coming in and which one felt better to me than it would be about which round.

Good luck to ya

Dober

Sounds like you had insufficient bullet performance, not an insufficient cartridge!