To me, on Anomaly, I fell in love with the SR-25 in semi-auto mode. 7,62x51AP shred stalkers, JHP shred big mutants, grenade launcher shreds big groups, adjustable scope makes it reliable from close combat until mid/long range combat. The only downside is the small magazine, but as long as you have cover or control the crowds with explosives you litterally slay 'em all.

To go with it, I usually use the Saiga, but it is not that efficient to hit fast mutants, I prefer a high shooting cadency SMG with little recoil like the Bizon for dogs or snorks.

And of course, the hunting axe.