If you are trying to do this to cater. I would suggest that you find out what is acceptable from the health Dept stand point and work back from there??
The biggest thing you are going to find is that you will need a commerical kitchen to work out of to do the catering thing, well legally. If that is not available you will be working as a "Private Chef".
Before you blow a couple grand on a cooker, determine the use and then find the one that fits that use. Think not just cost, but ease of use. How much do I need to babysit it. For a commerical gigs that is important.
and once you find that perfect cooker, buy the next larger one.
Good luck on the search.