Hey!
I take both alevel english lit and history so I should be able to help you out with this!!
Firstly, I wouldn't say one is more impressive to unis than the other - both are well received by unis due to their critical nature and the coursework aspect - both show off to unis that you are able to meet deadlines and work independently on a subject you are passionate about, so it doesn't really make much of a difference which you take in terms of university.
Secondly, they are both difficult, but in different places, so in my opinion for example, english lit content is much easier to understand than history content, however, strangely i find history essays much easier than english lit - the markscheme is really picky with literature, whereas it is less so with history!
Lastly, advantages and disadvantages... i mean, both are VERY time consuming, especially history in terms of content, and it is often difficult to know how to effectively revise english lit, however, I would say that english lit is good for a person who likes debating and having in class discussions as this is very much the dynamic of lessons in my school, and history is good for a person who is less into the full blown in class debating and is more interested in the cold hard facts and then judging what they think about them... for me, I would say that english is about your feelings and reactions and history is about your logical thoughts, so it really kind of comes down to the sort of person you are!
I hope this has helped at least a little, i tried to play devils advocate as both really are excellent alevels and i would recommend both! Let me know if you have any further questions and i'll do my best to answer them as best as i can!!