Hi Judith -
I've used both CJ and Linkshare and never had any problems with either, that I know of.
The reason I use both programs is because each affiliate operates through its own aggregator, so I normally don't have any choice. For example, HomeAway is a vacation rental site that I use a lot on my site. HomeAway operates through CJ - not Linkshare. If I want to be an affiliate of HA, then CJ is it.
I'd venture to guess that I've been using CJ for about 6 years. In all that time, I've never had a monthly payment delayed. They're "johnny on the spot" and always have my check to me before the end of each month. (Sure, now I've probably jinxed that!
On the rare occasion that I have had a "glitch" working with CJ, it's been because of the affiliate itself, not CJ. For example, Trip Advisor is notorious for not posting their transactions to CJ in a timely manner. (I can't blame CJ for that - it's TA's fault.) Every time that's happened, TA has eventually posted and CJ credits my account.
I've also found CJ's customer service pretty decent to work with. If I message them with a question or issue, it might take a day or two to hear back. But once I do hear from them, the customer service person sticks with me until my question/issue is fully resolved.
My experience with LinkShare/Rakuten is much more limited. I used to use them when Enterprise car rental operated through them. When Enterprise left LinkShare and moved their affiliate program to ImpactRadius, I followed Enterprise. At this point, I don't think I have any affiliates through LinkShare.
When you say that CJ is "crediting [your] account less and less", what do you mean? That you're making less money than you used to make? Or that CJ is only crediting your earnings to your account every few months?
Also, I'm curious to know ... what have you read about CJ that suggests they're less than honest?