I am looking for an R package for Gene Ontology enrichment. Basically, I want to give it a background list of genes and a foreground list of genes and test for enrichment in the foreground. Ideally, it would also do KEGG pathway enrichment and allow me to toggle on/off whether to include or remove duplicate genes. There seem to be a several different packages out there. I am looking for the best/easiest to use. Thanks.