Ok. I loved power rangers as a kid, still watch it occasionally because only samurai airs T_T. The original season MMPR had people who, somehow had more of a chance to save the world. Then of course the addition of the MMA fighter, Jason David Frank. The unmorphed fights in the one or two seasons were really exciting knowing that it wasn't just recycled footage from the Japanese.

I never understood the whole "sparks fly when hit" thing. There's a theory that makes sense; when a ranger gets hit, the suit reaches an overload of power causing the sparks to fly. Either way it does seem silly, but does add more effect that punches or no sparks at all.

The seasons In Space and Lost Galaxy weren't a favorite of mine because they really included more greenscreen effect. There were times when characters were falling out of the sky causing them to morph, and honestly I hate when I can tell greenscreen use.

The themes though, are pretty well created. Power Rangers music is similar to the Beatles; both styles of music change with the style of popular music. MMPR was in the 90's, so there were much rock and guitar features in the songs. Zeo was just a spin off of the first season so moving on.... Turbo again had a bit of that rock and roll that was popular. In space isn't really much rock, since I think creators were just looking for a theme that fit In Space. Lost Galaxy again was mainly to capture theme of season.

 Lightspeed, my favorite does include much rock and guitar in it.  Also, I will say the music through the season was brilliantly done. There was a large amount of soundtracks used in lightspeed that included a big and bold brass which does seem fitting for a military type service group. In parts where there is a bit more emotion, there is one song that I find so suitable for the moment.
On youtube, type "power rangers lightspeed rescue ryan saves the kids" and it is a powerful minute of good music.

Anyways Timeforce did have some of the last season's great music, with some of its own music. The theme of the show is a little bit about racism and working towards a better future, but also about making our own destinies and all that blah blah blah.
Wildforce's main standout was the Forever Red ep. Everything went downhill after Timeforce for me. When disney was in charge, the scenes just seemed more and more fake with the addition of superspeed, running in the air and on water, invisibility. When the megazords were being called out, they were all more like CGI, similar to Wildforce's zords. They all looked animated. Not to mention the corny and failed comic relief characters. I'm not going to say more because of how long I could review power rangers, but the show was good while it lasted