Hey!
Just like you I have applied for King's as well as Queen Mary University. I was rejected by King's as I did not do well in my LNAT either. But now, i have chosen Queen's as my firm choice. I have both attended King's and Queen's open days and I recently went to Queen's offer holder day. I can gladly say that I am happy choosing Queen Mary because if I got into King's there was going to be too much competition, although, there will be some competition in Queen's it will not be as much, this means that I can focus on my studies rather than focusing on competing with other students.
In addition, I went to both university's taster lectures, I don't know about you, but I do not like to be in lecture room filled with 100s of students. I feel like you will not get the attention you need if you don't understand something or if you want to ask a question during the lecture, you will less likely to get your question answered. However, in Queen's the lecture rooms were quite small so I assume that you will not get students no more than 30 in a class but I am not an expert I don't know how many people will be assigned to per class.
In terms of campus atmosphere, I can tell you that I have seen much better campuses. The university itself isn't in the best area of London since it is in Mile End. I was so worried about this and I was contemplating whether to put Queen's as my firm just based on this but I realised how wrong I was, at the end of the day, I will be in London and London isn't the safest place to live. The campus itself is huge, I got lost in it like 5 times. Accommodations are 100% better than ones in King's and is lot cheaper.
Plus, Queen's does one year in industry with a very famous American Firm in London. I don't know if you would be interested in that but it sounds amazing.
I hope this kind of helps.
Good luck.