The Guardian is by far the most commonly used logistics ship for armour gangs. As you'd expect from an Amarr ship, if offers a heavily low slot biased layout of 6/2/5 and by far the strongest powergrid, offering it the capability to fit a fierce armour tank as well as substantial repping power. The Guardian also receives 25m3 of drone bay and bandwidth, enough for a flight of light drones. As a dual logistics ship, the Guardian receives bonuses to remote armour repairers and energy transfers, as well as rep amount for armour rep drones.

Source: http://www.evealtruist.com/2011/10/know-your-enemy-logistics.html

• Logistics Cruisers I
  • Signature Analysis V
    • CPU Management I
  • Long Range Targeting V
    • CPU Management II
  • Spaceship Command III

• Amarr Cruiser V
  • Amarr Destroyer III
    • Amarr Frigate III
      • Spaceship Command I
  • Spaceship Command II

The Guardian is the first vessel to feature Carthum Conglomerate's brand new capacitor flow maximization system, allowing for greater amounts of energy to be stored in the capacitor as well as providing increased facilities for transporting that energy to other ships.

Developer: Carthum Conglomerate

While featuring Carthum's trademark armor and hull strength, the Guardian, being a support ship, has limited room for armaments. Its intended main function is to serve as an all-round support vessel, providing the raw energy for fleet compatriots to do what they need to do in order to achieve victory.

Logistics Cruisers Skill Bonuses (Per Skill Level):
15% reduction in Remote Capacitor Transmitter activation cost
15% reduction in Remote Armor Repairer activation cost

Amarr Cruiser Skill Bonuses (Per Skill Level):
150% bonus to Remote Capacitor Transmitter range
20% bonus to Logistic Drone transfer amount
60% bonus to Remote Armor Repairer optimal range and falloff

Role Bonus:
65% reduction in Remote Armor Repairer powergrid requirement
50% reduction in Remote Capacitor Transmitter powergrid requirement

[Guardian, New Fleet] 

Internal Force Field Array I
1600mm Steel Plates II 
Multispectrum Coating II 
EM Armor Hardener II 
Shadow Serpentis Armor Thermic Hardener 

10MN Y-S8 Compact Afterburner 
Conjunctive Radar ECCM Scanning Array I 

Large Coaxial Compact Remote Armor Repairer
Large Coaxial Compact Remote Armor Repairer
Large Remote Armor Repairer II
Large Remote Armor Repairer II
Large 'Regard' Remote Capacitor Transmitter
Large 'Regard' Remote Capacitor Transmitter

Medium Ancillary Current Router II
Medium Ancillary Current Router II

If you feel like blinging it up, by using some faction modules you can fit an Energized Adaptive Nano Membrane on for more tank. This will not result in increased reimbursement.

[Guardian, Test Machariel Fleet (Mixed Mediums)] 

1600mm Steel Plates II
True Sansha Thermal Armor Hardener
True Sansha EM Armor Hardener
Energized Adaptive Nano Membrane II
Damage Control II 

50MN Y-T8 Compact Microwarpdrive
Conjunctive Radar ECCM Scanning Array I

Large Coaxial Compact Remote Armor Repairer
Large Coaxial Compact Remote Armor Repairer
Large Coaxial Compact Remote Armor Repairer
Medium Coaxial Compact Remote Armor Repairer
Large 'Regard' Remote Capacitor Transmitter
Medium Remote Capacitor Transmitter II

Medium Trimark Armor Pump II
Medium Ancillary Current Router II