Hello. I am helping my father purchase an Autotrol 255 Valve Module and I noticed that there are two option I can choose from.
There is one that comes with the 460TC timer and one that comes with the 740 Logix timer.
I basically want to know what the best choice is.
Please let me know what the pros and cons are of each and ultimately which one I should be purchasing. Thanks.

460TC is a replacement for 440 timers, and is a little "simpler" to program.
It has improved drive motor, electronic timer, and only 3 drive gears ( old 440 had 8 and 4 that loved to break ).

And since we have been asked, let me say, once programmed and running,

There is no way to tell when the next regeneration will be, or when the last regeneration occurred by looking at the timer.
The Logix 740 upgrade 255, or Logix 740 upgrade for Performa 263,268 is a better design ( all the cycle times are controlled by the electronics ) , and since it uses a rear drive motor ( with 1 gear ) , it is less likely to fail mechanically.
It's a little more involved to program, and requires you know your resin capacity ( amount in cu.ft. ).

However, please NOTE: The 740 Logix is only available for use on the 255, 263, or 268 Valve Bodies, and if you have an older 155 or 163, 168, and just need / want to replace your 440 timer, you should use the 460TC or replace the Entire Valve Head ( with newer 255 or Performa 263 / 268 Valve ).

Review the information on the two ( we have photos, videos, copies of directions, etc ), and you can make an informed decision. Either will work.
see:
460TC timer assembly

and
255 upper valve body with 460TC timer


OR
255 Upper valve body with Logix 740 timer

740 and 760 Logix Timer Programming Instructions

AND The BEST would be the complete metered ( regenerates based on actual demand - water used ) control Logix 760 on complete new 255 Valve,
see:
Complete Valve Head 255 with 760 Logix Controller
and
Old Valve Replacement Guide / Directions