The best thing about ezlinxx is that their support team responds very quickly whenever there's an issue in our account, whether it be technical or not! I have used other quoting services before but none comes close when compared side by step for price/features comparison especially if you're looking at integrating this into Magento 2 like we are doing so far as of now (no contract has been signed yet). Nothing specific really; just make sure they can handle multiple quotes from different customers coming through one page - maybe ask them how many concurrent users doe I like that it is very easy for my customers, who are not computer savvy at all (they're elderly),to use this system without any problems! The customer service support from ezlynxx has been top notch also!! Nothing so far. Would love if they can make an app version of their software because some people don't have access or computers capable enought o run desktop applications anymore but still want quotes online asap. !