Favoring either of the Front+Rear Type-4 Launchers.
[X] Two Forward, One Aft (Mark IV) [24/72 Damage]/[12/36 Damage] [Cost: 164]
[X] Two Forward, Two Aft (Mark IV) [24/72 Damage] [Cost: 169]
Something else to consider in the Feddie's favor is that Starfleet's only really paying for the Feddie's weapons loadout once in the coming decades rather than needing to do it twice.
The big "New Fleet Program" refit that is supposed to occur in 2275 involves refitting older ships like the Excalibur and Attenborough/Atwater with the Feddie's current weapons loadout.
Whereas the Miranda (no way Starfleet's not procuring a bunch just because they are better than the Newtons in every way besides sprint) requires that they pay for both the initial weapons and then pay again when they swap them out to the Feddie's Type-V Phasers and Type-4 Torpedo Launchers.
That isn't a small amount saved even if stuff like Nacelles and Warp Cores, and Shields, are still going to need replacing.
Some quick napkin math using the below weapons loadout and costs from this
table:
Initial Cost
Phasers: 7*3=21
Torpedoes: 2.25*4=9
Total: 21+9=30
Refit Cost
Phasers Type-V: 7*4=28
Torpedoes Type-4: 4*4=16
Total: 28+16=42
Refit+Initial Costs: 30+42=72
Compared to the initial tranche of Federation Class Ships:
Phasers: 10*5=50
Torpedoes (4 Type-4's): 4*5=20
Total: 70
So it ends up that the Miranda's are going end up costing marginally more weapons wise
per hull for their initial ~3 decades of service.