Neither will trump the other in terms of 'reputation' (which is a pretty silly measure anyway as most employers dont read League Tables).
Go to Open Days - can you imagine yourself there? Which feels more comfortable?
Living on campus at a great Uni like Kent could be an amazing experience - and many people who live at home for their uni years often wish they hadnt as they do miss out on lots of 'student experience'. London is a difficult place to be a student - everyone is more spread out and there is less sense of community/socialising together. Living at Kent would still mean you could go home regularly - best of both worlds.