I will advice that you stick with Etheruem, Sui is just a new project, and do not buy on the hype, it takes many years for new project to stand and compete with the like of Ether, SOL, BNB, Matic etc. These set of old projects has long term investors with more investors buying not because its an old project but because etheruem among this projects has great features.
Etheruem is a big project that has the capacity to bounce back after it's market weakness this days. I am very confident that Ether will come back stronger .