I have used my Tangent Theta TT315M 3-15×50 for game (including jacks and coyotes) out to 1151, and on steel out to 1500+. Plenty.
If you want 20x, the S&B PMII 5-20x50US is great, but I don't think they fit on a LA without being mounted very high.
The S&B PMII 3-20×50US is another great choice, and has a bit more mounting length, but still not sure it will fit a LA.
So if you are thinking S&B PMII 3-20×50 MTC/LT (non-US), then weight jumps way up, and you might want to consider a ZCO 4-20×50 at that point.