Values for the client:
com_hunkmegs
Afaik the standard value of 56 MB does the trick for vanilla, some mods require a bit more because of additional assets. It’s hard to detect the exact value - maps are using different models/shaders etc. But let’s say a value about 64-72MB will fit all (including some MBs in reserve).
Run cmd /meminfo and do a search for “total hunk in use”. The value in that line shows the current used hunkmegs.
com_soundmegs
The standard value of 24MB is very low. This setting defines the size of the sound buffer memory. Cmd /s_list will show you infos about. From my experience a value of 160MB puts all sounds into that buffer and no I/O operations are done for sounds during the game 
com_zonemegs
No need to change this value.
–
The power of 2 thingy … I’ve found different statements about memory allocation in power of 2 steps. Some swear to do it this way others not.
Finally it’s up to your system/used malloc implementation but I don’t think any human will notify any difference here today. So give ET what ET wants:
com_hunkmges 64
com_soundmegs 160
If you still run into hunk alloc memory issues just add some MBs. Any higher values have no positive effect - it’s more the opposite case.