Ooft that's a tough choice. If you don't use VATS crits a lot (and don't have or don't want to get the perk cards to support them), then I'd say go for the mutants one as the fast fire rate with the increased damage from being mutated would do a nice consistent damage output for you, especially with the fast reload to get you back in the hame. Furious is also great though and would get you more damage overtime, though it's more ideal for higher rate of fire weapons :)

They're both awesome guns though!