If you're looking for an affiliate system then I'd probably listen primarily to affiliates since that's the purpose for having the system, right?
I like CCBill or Verotel programs. Zombaio is one I tend not to mess with. I would consider it if there were no choice or the program were a great converter.
Nats with CCBill paid option is also good. I like being able to get paid by CCBill. There are no individual minimum payments and my check is always on time. There is also a bit more trust.
Nats only. I still have a positive feeling about Nats but it's more of a question of the program owner. My rule is if I don't think you'll be sending me a check at least every month then I won't bother signing up if it's a Nats program.
MPA3 only. In the past (around seven or eight years ago) there was a shave module built into the old version of the software, MPA2. Because of this many webmasters are distrustful though some aren't. I used to not mind it and joined MPA3 programs but then suddenly a program I used crashed with their conversions and rebills and I started looking into the past shave incident and Mansion's response more closely. I opened a thread here summarizing what happened and asked affiliates what they thought about MPA3 programs. Apparently Mansion Productions had GFY remove my thread from the main area for some reason despite there being nothing slanderous in the thread from me. That has really made me distrust MPA3 programs a bit more because I don't understand why Mansion Productions would want to silence me if they have moved on and truly learned from the mistake. I asked Mansion Productions to restore the topic but to my knowledge they have refused to do so.
Further on the MPA3 program I was referring to as I said conversions dropped. But here's the funny thing. I notice some stray hits going to a "pay-per-unique" program in the stats display. And coincidentally if you take the number of hits going to this "pay-per-unique" program (which doesn't actually exist as the program only has revshare officially) my conversions would be normal again. Now I can't say for sure what is going on there. Perhaps somewhere my link codes are wrong OR perhaps something sinister is going on. I am usually very careful with my link codes though. Just some input from me. I'm not saying I would never join another MPA3 program but I'm sharing my thoughts and opinions.
PS- Don't do the no commission for affiliates cross sales on revshare. This isn't 2002. It pisses those of us who are left off and makes us question your honesty. Conversions are bad enough in 2013. At least don't show the cross sales on your revshare affiliate links. We deserve a commission for the sales we send you. Run a fair deal and it'll show in the numbers and we'll push traffic to you. It used to be called a partnership program for a reason.