For £170 you will be limited to what you can buy. For me the Manhattan HDR-S works fine for me and is under £170, it has the HD channels as well. www.satbuyer.co.uk
If you have broadband access and can afford the extra £80 then the Humax HDR1000S is worth a look it adds 7 day catch up TV for BBC, ITV, C4 and C5 this year.
I assume you wish to have a recording version.
There is information and user recommendations on the above website