Haven't seen any in full, but I loved the chunks I've seen of Changeman and Turboranger. Awesome casts, villains and action choreography.

While I havent watched but an episode or two here and there I have to say the shows that drew my interest the most were, Flashman, Maskman, SunVulcan, Turboranger, Liveman, and Bioman. Any ideas where to start?

Why all the 80's sentai have hight ratings than today ?

Because there were fewer channels. If you have X amount of people forced to choose between 3 or 5 options, all of them are going to be huge. Today you have over 100 channels available at any given time.

Flashman, absolutely Flashman. Sun Vulcan is good but it's not a show I would recommend marathoing because it's a product of a very episodic era. Bioman is a lot better in this regard - still pretty episodic but you can see traces of longer stories being inserted. It's basically the prototype for a show with an overarching plot.

But yeah, Flashman. Great premise with a fantastic payoff, wonderful villains and the stakes are huge due to the pressure on the Rangers this time around.

Thanks for the feedback. I started watching liveman and I am impressed with it. For example a early episode has the younger brother of a character who died in first episode shows up and asks red falcon to help build a car that his brother designed. Of course they build it and a monster poses it and I thought "oh god here we go again the kid is going to try and protect this monster car". However instead they use the designs to make their own super car live cougar to fight it. In the end the kid is just happy his brother designs were useful. I am used to something like zyuranger that has kids being dumb kids all the time so this was refreshing.

Thing about Maskman is that Takeru hogs most of the spotlight. Yes the other four have their featured eps here and there but at its core the show was pretty much Tom Cruise's Legend re-imagined as a Super Sentai show.
Still, fun show with an awesome theme song.