When comparing Active Texture Management vs Kerbal Engineer Redux, the Slant community recommends Kerbal Engineer Redux for most people. In the question“What are the best Kerbal Space Program mods?” Kerbal Engineer Redux is ranked 1st while Active Texture Management is ranked 9th.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Reduces texture memory use, including mod textures
All textures can be compressed & resized to save RAM. There are two modes of compression - basic and aggressive. Both compress to DXT and generate minimaps for all non-normal map textures, with aggressive mode having a max of 256x256 and basic mode having a max of 512x512 size for normal maps that it resizes to half the size.
Pro Can save vast amounts of space
In some cases up to 50% of space is saved.
Pro Aggressive mode eliminates the need for texture reduction packs for mods
Active Texture Management will optimize all textures to use less memory so there's no need to use separate texture reduction packs for each mod. It you choose to use texture reduction packs regardless, you might need to edit the config file at:
BoulderCo/textureCompressorConfigs/textureCompressor.tcfg
Pro Helps with designing functional and efficient ships
Pro Shows important statistics when building crafts and in-flight
Shows important statistics when building crafts (mass, deltaV, thrust, ISP - while on Kerbin, in vacuum, or on other atmospheric bodies) and in-flight (all of the above + periapsis, apoapsis, orbital period, time to ap, time to pe and many many more).
Pro Provides customizable in-flight readouts of flight data
Pro This is not an autopilot
As opposed to MechJeb, which is considered "cheats". KER helps a ton by providing already available info in a very accessible manner.
Cons
Con Extremely outdated and unsupported as of 2021
Most mods use .dds texture format which ATM doesn't work for, and the plugin hasn't been updated to recent versions of Unity.
Con ATM becomes ineffective as most mods texture file use .dds format
Con Slight increase in initial game load time
Con Adding more system memory might be a better option now that KSP support 64 bit
Con Less readable than some alternatives
The same information is presented in a more intuitive and readable way by DMagic's "Basic Delta V" and "Basic Orbit".