I have been using Marcus by Goldman Sachs' HYSA for the last 3 years now. No complaints at all, great customer service, and simple app UI. The best part is that only Marcus provides additional APY on top of the standard market interest rate via their referral program. That's a great bonus. Right now they have an additional 1% APY on top of the existing 4.5% APY, which takes it to 5.5%. Act fast as the Federal govt will be bringing interest rates down in 2024. Make sure you utilize the high HYSA rates available right now. Here's my referral code: https://www.marcus.com/share/SHI-NS9-N7A3