What Stack Exchange site should I use to learn English to an advanced level?
You probably want English Language Learners if you’re learning English as a second language:
English Language Learners Stack Exchange is a question and answer site for speakers of other languages learning English.
If you’re a native speaker, and looking to dive into advanced aspects of the English language, then English Language & Usage sounds more appropriate:
English Language & Usage Stack Exchange is a question and answer site for linguists, etymologists, and serious English language enthusiasts.
There are questions spread across the various Metas about whether a question should be asked on ELL or EL&U:
- How do I determine whether a question fits on English Language & Usage or on English Language Learners?
- Drawing the lines between ELL and EL&U
Note that, of course, you should only use these sites for asking questions about English and/or difficulties you’re having while learning. Don’t expect tutorials or teachers – that’s not what Stack Exchange is for.