I would also recommend the Topfield from personal experience. I have found it very reliable. The Sony is an overpriced piece of badge engineering.
Serious choice is bewtween the Humax and the Topfield IMO.
Marcdavies' excellent chart might be useful;
http://www.pvrjunction.co.uk/compare/
Some differences between the Humax & Topfield
Price; Humax is cheaper.
Humax does auto timer padding out of box; Topfield needs an added TAP*
Topfield has interactive enable/disable feature.
Topfield has time shift (auto buffering feature) enable/disable feature; this saves unneccessry hard disk activity if like me you do not use this feature.
Humax has limit on MP3 storage. (5GB)
Topfield can organise recordings into folders; Humax cannot;
70 timers available on Topfield, 50 on Humax.
Component video output on Topfield (via scart).
Topfield is fanless; so may be quieter; but as a result needs to be positioned with a little more care.
The Topfield is smaller; which could be disadvantage or advantage. You could not easily stack anything on Topfield (unwise anyway see no fan above).
Topfield comes in 160Gb and 250Gb versions. Humax 160Gb;
*Taps (Topfield Application Programmes). USB downloadable almost all free programmes that can be run on the Topfield to change many aspects of how they work, including alternative EPGs with e.g. almost instant info and features such as recording series by name search.
Both are expected to be able to make use of Freeview Playback series link etc information by future software updates. Humax may well be first with official software but TAP authors are already making the existing information work on the Topfield.
Hope that is fair but I have not used a Humax myself only the Topfield.
Richard