Hi, most [if not all, apart from some business packages] ISP's will cap or have in place a fair use policy [FUP]; having said that, I spend several hours a day on the net browsing and listening to music and I rarely use more than 5Gb per month, so unlimited I would say it not really an issue for you.
In your shoes I would go for reliability; connection quality and solid tech support, and for that I personally would consider NewNet or some of the Enta resellers - both have very good reputations and great support on all fronts.
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HTH - Blue