Depends on what features you want (or need) but mostly SlickStack is considered better for single-site high traffic, or a “money” site that you really want very strong security and many things hardcoded.
WordOps is better if you want a user friendly UI interface and want to put many sites on the same server, maybe for your customers.
SlickStack does not support installing many single WP sites.. it supports only WP Multisite.
