For general use, we strongly recommended the English stemmer.
Implementations of Beth Lovins' English stemmer from 1968 and Martin Porter's original English stemmer are provided largely for academic interest. The original Porter stemmer might conceivably be useful if you're wanting to reproduce results which used it.
If you're stemming English from the time of Shakespeare or the Authorised Version of the bible, the adjustments to the English stemmer to better support "early modern English" are likely of interest.