Favorate Power Rangers series.

[lurkon]

I have to say Zeo. Zeo had my favorite theme song, and while the shape zords weren't really my favorite, I still loved the series. I need to find some time to watch some of the more interesting looking later ones. I enjoyed In Space and Lost Galaxy, but slowly lost interest until I stopped watching around... Mystic Force maybe?

 

[Marik2]

Time Force, SPD, In Space, and Lost Galaxy are the most memorable ones for me.

 

[Souplex]

I'mma say Lightspeed Rescue.
It was very down to basics. No extraneous continuity fluff to scare off new viewers, but actually good. (Unlike Mighty Morphin' which is only good when viewed through ironic-kitchy-nostalgia-goggles.)

 

[Vausch]

Lightspeed Rescue because Carter is a badass.

And In Space, since it was well written and took the scale of the show to new levels with a universal invasion.