I recommend you listening to this,this or this while you read.
Maud (Degtyaryov-28 LMG + 2 grenades) (3 47-rounds-magazine (a total of 141 rounds) + Highest damage per bullet + Decent fire rate (550 rounds per minute) + Mid-High HP + Able to pin enemies down with a constant burst + Longest effective firing range (800m/874.9yd) - Slow movement speed - Low-Mid accuracy - DP's barrel might overheat if firing for too long non-stop - Relatively long reloading time * Can swap her DP-28 for a german MG-42 or MG-34 if found on another dead soldier (Not recommended to rush in the front, she's a support unit)
Pinkie (Captured german Sturmgewehr-44 + 2 grenades + 1 AT grenade) (3 30-rounds-magazine (a total of 90 rounds) + Low-Mid HP + Decent fire rate (550-600 rounds per minute) + Fast movement speed + Immune to pistol or SMG headshots + Decent accuracy + Ideal effective firing range (300m/328yds) - Ammunition cannot be found easily - Doesn't blend well with snowy areas * Seeing her comrades die slowly turns her into Pinkamena, which might affect her accuracy to the better or worse (Differently from Maud, Pinkie is an assault unit, which means she storms the front)
Marble (Pistolet-Pulemyot Shpagina 41 + 2 AT grenades) (3 71-rounds-magazine (a total of 213 rounds) + Low-Mid accuracy + Very high fire rate (900 — 1000 rounds per minute) + Immune to cold, snow, ice, etc + Can use the knife for silent/stealth kills + Relatively difficult to see when on the snow - Moves slower and sprints for less time on summer/hot weather - Doesn't blend well with the ambient (forest/urban areas) - Lowest damage per bullet - Poor effective firing range (150m/164yds) - Accuracy drops terribly while moving (best choice is to crouch while firing) * Doesn't make any sounds when shot/sprinting/reloading (only when dying) (Similar to Pinkie. She's an assault unit, but for closer fights, mostly to eliminate soldiers with bolt-action/semi-automatic weapons)
Limestone (Nagant M1895 “Officer’s model”) (35 rounds (7 can be loaded at the same time) - Low Hp - Worst main weapon out of the 4 sisters * Keeps encouraging or threatening soldiers among her, which gives them 20% more HP, movement speed, sprinting time and accuracy * Can shot and kill one of her own soldiers, which makes the others fight better * Can take command of any land vehicle * Do not take any enemies as prisoners * Can call in an off-map Katyusha barrage on a specific location (A 100% support unit. Can't fight without other soldiers to command)