I'm with vilefoxdemonofdoom: rip the LPs at the highest quality your kit/software supports (ideally, lossless).
The resulting files will be huge, but you can always create much smaller copies with a lower bitrates for use on a phone or MP3 player using converter software (just Google something like "lower MP3 bitrate free software" or you may be able to use Windows Media Player). I use a converter on podcasts which cuts the file sizes by maybe 50% on average - podcasts really don't need to be that high a quality.
Re the £30 USB record players, my mother - who is as technically incompetent as you can get (calling a mouse a hamster, anyone?) got one and managed to convert all her LPs so it must be absolutely idiot proof.
