I'll put my 2 cents in about net zero.
I think it's the easiest system to use. I am in 6 fellowships. 3 use email chains, 2 use netzero, and 1 uses shout-outs.
In my fellowships with email chains, every time I log in, there are multiple messages waiting to be read. I open it, peruse the list, and decide who to donate to, after checking my AW to see how much room is left. Then I have to reply to the message, close out the email system, then re-open to make sure I didn't post at the same time as someone else, then donate to the person. And repeat that several more times until I have all donations done. And then, when the AW is close to being done, check to make sure all chests are taken, and that I don't donate more than I have room for.
It's not hard. But it is a fair amount of work.
Compare to netzero. Every time I login, there may be one email message waiting. Sometimes there are no new messages. And sometimes there are 2. I go into the netzero message, and open the indicated wonder(s) and donate the amount of the next chest. I do not have to write anything or get out of the messages and reopen. It takes way less time and effort. The only time I have to write a message is if I take the last chest on an AW. And that is a quick copy/paste, and then add "DONE" to the message. When it is time to list my own AW, I simply copy/paste, then add my AW on the top of the list. And then when it is finished, double check everyone's math, post in the admin thread if there are errors, and I'm done.