Probably my favorite scope for big game is the Leupold
2-7x33. The 3-9x40 is also very nice but I wouldn't want anything larger than 40mm on a big game rifle. I usually sit with the scope on 4x and only crank it up for volunteers past about 200 yards.
This summer I sat with a bud looking over a bean field with my FN Mauser 7x57 with a fixed 4x Leupold
on board (crop damage permit, strictly legal). A volunteer came into view at 200 yards. When I brought up the rifle I thought that deer looked mighty small through that scope! That's when I would have reached up and cranked the mag ring on a variable. I did kill the deer though.
Now I don't often shoot on 2x. Only when sitting or moving through the thickest of the thick. I have never kilt a buff or elephant but I can understand how low magnification would be beneficial there. A diaper and a roll of toilet paper would probably come in handy then too.