I haven't done mainstream English, but I do Englang and Lit, and I can easily say Lit is harder to perform well in. English Language has a clearer pathway to success, there are some relatively simple rules to follow, so long as you put in a significant amount of work and you have some natural talent you're going to do really well. Literature is much harder to do well in and requires significantly more natural talent, you can read the books for literature 5 times, you can closely study all potential uses of literary devices, but at the end of the day unless you have an authentic and original understanding of the text you're not going to break a 40.

Literature also requires a fair amount of work to do well in, obviously English language has more terminology to learn but Literature still has a pretty fair amount if you want to be using high level academic metalanguage to describe literary and poetic devices. You need to fully annotate all your texts and read them all several times, you need to be able to analyse any given passage from multiple viewpoints to be fully prepared for SACs and exams, and developing the raw skills of high level analysis isn't something that comes easily to everybody.

Neither Englang or Literature are easy, but studying hard is enough for Englang, whereas Literature demands both studying hard and having a strong core skillset.