The ones I need, otherwise I always prefer core HA elements if possible.
With recently UI improvements in HA I have actually removed several HACS
The ideal case for me is that I don't need HACS at all. My experience has been the same - I've happily been able to switch to core HA components and stop using HACS ones. It's great to see HA is not idle with success, they are continuing to make new features even when backwards compatibility may break.
Mushroom cards
Local Tuya - so I can control my Tuya Devices without needing the cloud.
Wyze - I have a couple of cameras which are Wyze so I use it for those. I'm not against the cloud for some things. :)
Spook - not your homie -- When I deactivate or rename a device (seasonally), it lets me know which dashboards need updated for example.
Playstation Network - so I can show what my PS5 and PS4 are doing while active.
Several other items such as themes I've tried out and probably more I've tried but never removed.
The VsCode plugin
Are you looking for integrations or front-end/GUI recommendations? HACS is great for both!
pyscript.
Bubble card. Recently redid so much using it. Different than mushroom cards so both complement.
Home Assistant is open source home automation that puts local control and privacy first. Powered by a worldwide community of tinkerers and DIY enthusiasts. Perfect to run on a Raspberry Pi or a local server. Available for free at home-assistant.io