Siteground Vs Fastcomet For Cs-Cart Hosting

Which one would you recommend between Siteground and Fastcomet for CS-cart hosting? We will be going for a VPS with minimum 8 GB RAM and 100 GB SSD space. We have 50 to 60 concurrent users anytime and expect it to go upto 200 to 300 concurrent users.

Our requirements :

A fast and perfectly configured server setup with all the required cache and web server system.

Quick and responsive support through tickets, no phone support required. For critical issues like service outages, web server down etc we expect response and action within 2 to 5 minutes. That is what we have been getting with our current hosts but they don't have a datacenter near our region. So we would like to move out.