Well, I haven’t experienced the alternatives to be honest.
The BGS course material is good, but then I prefer ‘books’ to electronic anyway.
I think their ‘renowned’ question bank lets them down now, mainly because of the switch to the 2020 syllabus.
CAPT have a good reputation and their online sample exams seem representative of the newer questions.
Certainly worth a look.
The ATPLquestion online system is excellent.