...well, I mean, *I'm* going to tell you to watch either Abaranger or Go-Busters.... :D For the reasons outlined above. (But I really like mood whiplash in my media, as long as it pairs campy with dramatic in a way that feels respectful to the characters involved.)
Gokaiger is in fact quite brilliant, but a lot of the fun of the series is in its guest stars, who are actors reprising roles from former Super Sentai series. There's also the use of the suits and mechas from previous series. If you're not familiar with at least some of the other shows, you're missing out on a lot of the emotional impact. For that reason alone, I respectfully disagree that it's a good first Super Sentai series. (Although it was seriously really, really good. Just watch some of the other ones first, I think.)
I would say, though, as someone who hasn't seen Super Sentai at all, to start with Dekaranger (from 2004). If you've seen SPD, you're familiar with the concept and with a lot of the episode plots, but in this case you'll see where Dekaranger succeeded and SPD (despite being enjoyable) fell kind of flat.
If you're looking for a classic series, Bioman (1980-something) was quite good. Timeranger (2000) was excellent; it's another one where the Power Rangers adaptation was really close.
Hurricanger (2002) was good if you like ninjas (although it did that thing where they had a bunch of former super sentai actors as guest stars, so if you're NOT familiar with the shows of the 80s and 90s you're missing a lot of the fun in the Shurikenger episodes).
I also really enjoyed Boukenger, although a lot of the fanbase found it boring as fuck (I think part of that was because their Red was super chill, which is really Not Normal for Reds past like, 1998).
If you liked Power Rangers: RPM, DO NOT WATCH GO-ONGER. Just don't.
Kyoryuger I've made secrets about (strong finale), but it's fun if you want a new-ish series. ToQger was fucking adorable, but the mechas and suits made me cringe (and usually I do not care about the mechas at all).
You could also watch Kyuuranger, the current series, but I would not recommend it. If you do, please remember that Lucky is the plague of Kyuuranger and try not to hate the entire franchise because of him.
OP
Gokaiger is in fact quite brilliant, but a lot of the fun of the series is in its guest stars, who are actors reprising roles from former Super Sentai series. There's also the use of the suits and mechas from previous series. If you're not familiar with at least some of the other shows, you're missing out on a lot of the emotional impact. For that reason alone, I respectfully disagree that it's a good first Super Sentai series. (Although it was seriously really, really good. Just watch some of the other ones first, I think.)
I would say, though, as someone who hasn't seen Super Sentai at all, to start with Dekaranger (from 2004). If you've seen SPD, you're familiar with the concept and with a lot of the episode plots, but in this case you'll see where Dekaranger succeeded and SPD (despite being enjoyable) fell kind of flat.
If you're looking for a classic series, Bioman (1980-something) was quite good. Timeranger (2000) was excellent; it's another one where the Power Rangers adaptation was really close.
Hurricanger (2002) was good if you like ninjas (although it did that thing where they had a bunch of former super sentai actors as guest stars, so if you're NOT familiar with the shows of the 80s and 90s you're missing a lot of the fun in the Shurikenger episodes).
I also really enjoyed Boukenger, although a lot of the fanbase found it boring as fuck (I think part of that was because their Red was super chill, which is really Not Normal for Reds past like, 1998).
If you liked Power Rangers: RPM, DO NOT WATCH GO-ONGER. Just don't.
Kyoryuger I've made secrets about (strong finale), but it's fun if you want a new-ish series. ToQger was fucking adorable, but the mechas and suits made me cringe (and usually I do not care about the mechas at all).
You could also watch Kyuuranger, the current series, but I would not recommend it. If you do, please remember that Lucky is the plague of Kyuuranger and try not to hate the entire franchise because of him.