In Space is my favorite season. I guess it was the first season where the plots got a little more deep. The villainess was completely human and not entirely evil. Even Ecliptor, who was basically a monster of some kind, wasn't entirely evil, he was capable of loving, the way he did Karone. The ending was great. I loved how the broke the whole secret identity rule by just morphing in front of everyone.
I didn't watch it when it was being aired for the first time because back then, I had stopped watching Power Rangers for about three and a half seasons, since Trini, Zack and Jason had left. I watched one episode one time, when it had already started and since I hadn't had a clue what had happened in the series and I didn't see Tommy or anyone known, I didn't know it was Power Rangers until they mentioned morphing. Anyway, I watched it all and I decided to watch more, so I ended up recording all the reruns. It was the season that got me back to watching Power Rangers and I haven't stopped since.
So to me, it's the best!!!