Voyager is definitely the most polished and great for those who used Apollo for Reddit. It is also very actively developed. For the Android users who do not mind the iOS aesthetic, Voyager is one of the few Lemmy clients on F-Droid.
Thunder is also a great option. I personally prefer its UX more than Voyager, but it is not quite as polished.
Ladybird is still very early in development and is not even targeting an alpha release until 2026. There are no binaries currently available, so the only way to even test what currently exists is to compile the source code. I am excited to see a new competitor, but I also do not have high hopes given how difficult it is to meet all of the web standards. Given the increasing number of websites that have problems or limitations with Firefox, I do not foresee Ladybird ever getting to the point where it could be reliably used by average people. I would love to eventually be proven wrong about this though.
Servo also has nothing to do with Mozilla anymore. It has been a part of the Linux Foundation since Mozilla laid off all of the developers in 2020.