I've only done a few hours in both types (I've been operating Decathlons for many years for tailwheel and aerobatic training.)
A small number of Zlins were imported in to Australia many years ago. The last one operated by a flying school ceased when fatigue life prevented any further aerobatics until some costly work was done. As far as I know there is still one operated privately here but that fatigue life is an issue for it. Others here should know more about the fatigue issues.
Robins/Alphas are fairly popular in Australia for that role - ab initio / basic aerobatics. Four different schools and about half a dozen aeroplanes and all operators are happy with them. One locally here was purchased just prior to the company going into receivership (three ordered but only one delivered) and I'm unaware of any new aeroplanes been completed since. It seems that spares are still available however I believe that this one has been sitting on the ground for the best part of a year waiting for a canopy transparency. Worth asking how many new aeroplanes have been delivered to customers in recent years.
One school near Sydney operates a small fleet of Citabrias for ab initio and they've been going well for many years.
Hourly rate for the Robins and Citabrias are competitive with other types of that size; the Zlin was much more expensive to hire when it was available here so not really viable for ab initio.