WF, NS, and DT are the best bar none (and yes, I count WF despite MMPR Productions still shooting the series somewhere else)
NS is the best parody of the series ever, which sadly the juvenile fandom mostly does'nt "get" or appreciate and runs down making total fools of themselves in the process, whilst fans who understand the season enjoyed it's tounge-in-cheek humour and fourth wall breaking.
DT acknowledged PR's Sentai roots, had the best villain since pre-marriage Lord Zedd and Dark Spectre, had excellent storylines that made the most out of the NZ locations, had one of the best (and the only good) Disney team-ups ever, and closed out with a quiet finale which does'nt deserve half the **** it gets
SPD and MF are, of course, the best example of how to turn PR into a train-wreck of global proportions. SPD may have had one of the best casts and concepts ever attempted in PR, and MF had ten or thirteen excellent episodes, but both sadly became little more than explosion-filled fillers and Sentai translations so much that the ideas used meant nothing.