I was just thinking yesterday that if somebody wanted to get into Sentai, i'd probably recommend Jetman. It's a good introduction to a lot of the tropes that make the show what it is. It also has good character development in both the heroes AND the villains.

The only 2000s Sentai i've seen was the first episode of Gekiranger, which was good. But for series, i've only seen 90s and 2010s stuff.

All Time Super Sentai Favorites
 

From Zyuranger to Megaranger were my all time favorites

My favorite Sentai of the 2000s is Gekiranger. It's also my favorite Sentai in the franchise.
I've never finished an 80s series, so I can't name any favorites, while my favorite 90's series is easily Kakuranger, with it's great mix of comedy, drama, and it's high action with awesome designs. Loved it.

I got 9 episodes into Kakuranger and thought it was really boring. The only parts I actually liked were seeing the different yokai each week (I looked up what they were based on) and the 60s Batman-esque BOOM and POWs. I'm sure i'll give it another try sometime and like it more though. My expectations were a bit off since I had just finished my first series, Zyuranger and basically wanted more of the same.

Watched Ninninger 21 earlier. It...was another episodes of Ninninger. I liked the focus on Star, but other than that it was just a plain episode. Also, after 2 episodes of Lion Ha-oh, i'm sick of seeing the word transcendent.

Not that much of a Jetman-Fan myself. It's not that I didn't like or enjoy it, but I just enjoyed many other shows in the franchise a lot more (and a handful much, much less).
As for favorites from each time, I'd go with Liveman for the 80's so far- but then again, I've only seen Sun Vulcan and Liveman from that time, so yeah.
For 90's Sentai, I guess I'll go with Gingaman, though Kakuranger and Megaranger are pretty close. But Gingaman was a typical Kobayashi show AND had a fantasy theme so that sure makes it an obvious choice.
As for the 2000's, Abaranger would be my Sentai of choice, though I liked most shows from that time a lot (except for Boukenger).
My favorite from the 2010's aka now is Goseiger, the one that started this decade, because it's my favorite Sentai after all. But so far, there was no show in that time I didn't enjoy so... Go 2010's Sentai!

Saw the second episode for Jetman. It was a decent episode with some pacing issues. It was cool seeing Ryu fight a giant monster outside of a mech. Another thing about the group fight, did Gai really grab that mook's privates?

like I said, Jetman is better in bursts.

and yeah, Gai does a lot of things that are nuts. Gai doesn't need to play fair.

Technically Goseiger ended the decade since a decade is 1-10, not 0-9. There was no year 0. As such, Gokaiger kick started the new decade.

Well, I think it's really a matter of how you calculate as it was still airing in the first months of 2011. So you could count those seasons from the 0 year to both of decades, depending on how you define it...
However, the rest of the argument still stands as it was referring to the following seasons so yeah. I don't think it was that important to correct me there.

I don't know...the 90's are considered to be 1990 through 1999, 80's are 1980 through 1989, and so on and so forth. So the 2000's are 2000 through 2009. Those are all still ten year blocks of time or decades. It doesn't make sense to say that 2000 is part of the 90's.