Both are good in 2024 - generally if you're botting a main or just 1-2 accs, then mirror is good for you. If you want to potentially make a goldfarm with many accounts then stealth is for you.
Mirror mode sacrifices speed for safety. So if you care about more safety then mirror is for you. But it's not possible to get maximum speed, and it will use more resources (including both cpu and memory) whereas stealth is more lightweight. If you prefer lightning fast tick perfect then stealth is for you.
Stealth has invokes so I am biased there and it's currently my favourite, but I used mirror from 2014-2023 and it served me well, now I'm fully stealth, and I am glad there are two clients to choose from, because I can easily switch to mirror. In fact when I test scripts I use mirror mode.