Hi Nikki,
According to James Taylor (who knows a thing or two about winching) the Brano winches are pretty good. I doubt there is much difference between Brano and Tirfor. Mine, on the other hand is of no decernable make, but was way cheaper than the other two, I bought it new from a company on Ebay. It has the CE saftey mark, so I trust it. If you want, I can give you the name of the supplier. They seem pretty efficient. If you were to go for the small one, "JT" recommends a swingaway smatch block (pulley to non-offroaders) to double up the pulling power. I don't think I got the best deal on mine though, so I won't offer to give you the suppliers details. I'm sure someone here can suggest somewhere decent.
Its bloody good fun, as it means you can winch massive logs closer to stuck Land Rovers and get yourself in situations where you have no hope of getting out when the saftey pin breaks!
Guy