the mcmmo features are features which makes it that you get 2x (mcmmo plus) 3x (mcmmoplus 2) and 4x (mcmmo 3) of the exp for mcmmo stats when leveling up.
The bonus plus features make downtime for using features such as serrated strikes or beserk less and gives you extra time when using it.
The more upgrades, the better.
ExtCommandsPlus2 has several features:
1) It has automatic truster e repairs, your tools won't break.
2) It has the /nv command which enables nightvision.
3) It has the new /condense command which can be found on the news page (I believe it changes ingots to blocks i.e gold ingots to gold blocks without crafting tables).

ExtcreationsPlus has cooking pots and I believe you can change paintings to what you like them to be with it.

 

There is also a page on the wiki that explains all of the donations and their commands, here is a link: www.tinyurl.com/ECCsupportercommands