I disagree about the developer usage.
1L of Ilford Multigrade developer is good for developing something like 2-4 square meters of paper. Most amateur users will definitly not exhaust that in a session.
Stored in proper(!) bottles, you can use it perfectly fine for multiple sessions. Thats what i do.
Proper plastic bottles for chemicals can be had very cheap and are totally worth it.
Mostly HP5. Because it’s just so damn flexible.
Will get me a bunch of Foma films for some experiments in the near future though.