Need Help!- which motor has the beter spec for a servo

[eloid]

I have 4 servo motors which are simular, there all dc motors which i
think are good canadates for adding encoders, the motors frames are
84.5 mm sq..face which i think are nema 34 compatable

which motor has the better spec and why?

spec are as follows
motor1

skewed rotor design yes
maximum operating speed: 4200 rpm
continuous torque: 1.2N.m whats this in oz/in ?
torque constant (KT): .1757 N. m/am
peak torque: 6 N.m whats this in oz/in ?
voltage constant (KE): 18.4 volts/100rpm
terminal voltage: 72 VDC - resistance: .68 ohm
continuous current: 7.6A - inductance: 2.35 mH
peak current: 38A - weight: 8.8 lbs
inertia: 3.39 kg.cm^ - 7 inches

motor 2

skewed rotor design yes
maximum operating speed: 4200 rpm
continuous torque: 1.2N.m whats this in oz/in ?
torque constant (KT): ? N. m/am
peak torque: >12 N.m whats this in oz/in ?
voltage constant (KE): ? volts/100rpm
terminal voltage: 80 VDC - resistance: ?ohm
continuous current: 9A - inductance: ?mH
peak current: 80A - weight: 8.8 lbs
inertia: 3.39 kg.cm^ - 7 inches

motor3

skewed rotor design yes
maximum operating speed: 4200 rpm
continuous torque: 1.2N.m whats this in oz/in ?
torque constant (KT): .1443 N. m/am
peak torque: >12 N.m whats this in oz/in ?
voltage constant (KE): 15.12 volts/100rpm
terminal voltage: 72 VDC - resistance: .52 ohm
continuous current: 8.8A - inductance: 1.83mH
peak current: 80A - weight: 8.8 lbs
inertia: 3.39 kg.cm^ - 7 inches

motor4

skewed rotor design yes
maximum operating speed: 4200 rpm
continuous torque: 1.2N.m whats this in oz/in ?
torque constant (KT): .1757 N. m/am
peak torque: >12 N.m whats this in oz/in ?
voltage constant (KE): 18.4volts/100rpm
terminal voltage: 90 VDC - resistance: .52 ohm
continuous current: 7.6A - inductance: 2.35mH
peak current: 80A - weight: 8.8 lbs
inertia: 3.39 kg.cm^ - 7 inches

A quick question, Is the inductance directly related to how strong pm
feild is?

[Al_The_Man]

They all appear to be suitable candidates, I assume you mean DC Brushed?
If you google for a converter, you will see dozens e.g. http://www.cleavebooks.co.uk/scol/cctorq.htm
The inductance probably originates from the amount of magnetizable material within the coil at/under the comm position.
Al.

[eloid]

yes dc burshed