Ok, I just feel this needs to be pointed out:
1) Which college/s you'd enjoy more is obviously going to be highly subjective, so asking us 'What do you think of my list' is going to get different answers from different people. For example, most would tell you that UniCol is a bad idea, while I (who went there) reckon it's a great hall.
2) This really isn't that difficult. Pick your favourite college, put it as your first preference. Then pick two colleges that *aren't* the 'Only really accept first-choicers' colleges (ie: Carrington, St Margaret's, Knox, Selwyn, Arana, probably (to a lesser extent) Hayward are all BAD second/third choices) that you wouldn't mind living in.
It's all really up to you, and what you value most. For example, if you want to be super close to/on campus, the likes of UniCol and St Marg's would be great for you. If you want to already know 50% of your second-year med class before starting med, Carrington would probably be a good pick.