As long as you don't use one with metal to metal threads, they are quite comparable. CSUSA has fancier and more expensive kits than Berea, but not always a very good plating selection. Berea generally has a good plating selection. Just be sure you don't use 24K, 10K or Upgrade Gold because none of them will last.
Which kit you use will depend a lot on the customer's preference and since you're never made one it will be hard for the customer to see how it feels. I had a customer who was pretty insistent that he wanted a Baron because he said he had small hands, but when he actually tried it out and also tried a Churchill, he bought the Churchill. I would suggest you get a Baron kit and Churchill or El Grande and make them so he/she can try them out.