https://wiki.gbatemp.net/wiki/Wii_cIOS_EmuNAND_Compatibility_List
For WiiWare channels :
use Full for everything, only 10-15 are not working at all and requires neek.
that list might be wrong as users reported the "d2x version" instead of the base.
first, try games with different base (56, 57, 37, etc.), then if no bases are working, use neek(2o).
Usually, based on most wanted games people want to play, Castlevania ReBirth has an issue, and bonsai barber.
For VC N64 :
Try different bases. If you look at the list, most games are working with cIOS rev17 (which were forced to use base37), so use d2x base37 too !
or use neek(2o) if you don't want to try.
For Wii disc-based games :
either OFF, or partial if you want the savegame on your emuSave Path (sd or usb), except for Zelda skyward sword and metroid prime 3.
EmuNAND channel is the setting and the folder where you store your VC/Wiiware .... "channels" (I'm sure you knew it!)
VC/WW's savegames are ALWAYS on emuNAND, the place where the channel's data is located.
if you set to Full (default), it uses the full emuNAND folder (games, settings, Mii, Wiimote sync, etc.). This is what you want most of the time when playing a channel installed on emuNAND after doing a full NAND dump.
if you set to partial.... please, don't. it's a mix, with mii and settings read on the real NAND, ticket from real NAND..... channel and savegame on emuNAND. it could be useful... it could be a mess ..... I'm not sure. you shouldn't bother unless you understand the consequences. It might require that you once installed the same game to sysNAND or it might not work. it's useful for .... maybe having the mii, wiimote and network settings read from realNAND ? that's all.
if you set to Neek, it'll reboot the console into Neek mode, if you have neek it'll stop at system menu, if you have neek2o it'll autoboot the game.
Full and partial and run from sysNAND, using cIOS d2x, with the base you installed in the slot you chose.
Neek on the contrary is using only the official requested IOS, in a full sandboxed environment, no cIOS at all.
EmuNAND save, is the folder where you have your Wii disc based savegames (only Wii disc !!!! not VC/WW Channels!)
EmuNAND save affects only Wii disc-based games. NOT VC/wiiware/eShop.
If you set to OFF, the savegame is on the console.
if you set to Partial, the savegame is on emuNAND save folder. You don't need an NAND DUMP in that folder, only the savegame will be redirected and read/write here.
if you set to Full, you need a full NAND dump in that folder, and it'll use EVERYTHING from there (Mii, wiimote sync info, Wii settings, etc.)
You can separate the two folders (emuSave and emuChannel), for example Wii disc saved on SD card and Channels on USB for storage space, or you can use the same folder for both.