Without hesitation, RE!
I personally didn't do Computing, but I heard it's quite hard and you have to do a bit of work, especially as you actually have to learn to code :O
It's a lot easier to regurgitate from the textbook in RE than in other subjects, because the way you answer the questions is very structured, also there's no coursework like there is in Computing, so you could save yourself from extra work :P
Unless you want to do Computing later on (which you expressed you don't), employers don't care about anything else other than English and Maths GCSE's, so RE is on the same level as Computing at GCSE, but it takes a lot less effort to get the A* in RS, like I did, and also you enjoy it more anymore so it's a no brainer.
Pick RS.