I'm glad you enjoyed Dairanger, which is one of my favorites as well. As for what you should watch next, do you have any preferences? If not, here are the sentai series I've watched and would recommend:

Dekaranger
Magiranger
Shinkenger
Timeranger

I think I'm going to go with Dekaranger next. I've watched the first two episodes and I'm enjoying it a lot. I know it's supposed to be pretty episodic and lacking in strong villains, but the characters seem like a lot of fun so far. Honestly, the only downside I'm seeing so far is the terrible animatronics on Doggie's head and I'm pretty sure I can live with that.

I watched episode one of Sun Vulcan this morning.
...Wow. I know not to harp on special effects from early 80's Toku (I'm a major Godzilla fan :P), and they're not bad. But there was just something about it that made it a drudge to sit through.

That said, I love the suit designs, the characters aren't too bad (VulEagle was kind of boring with a constant serious expression on his face except for one moment where he laughed, VulPanther's eating schtick I can live with, and VulShark got nothing but the narrative telling us what he could do), the fight scenes were decent (There was a lot of punch -> Scene cut -> Enemy getting hit, which I'm not a fan of), the mech was neat (Though it being separate vehicles seemed a little unnecessary), and the monster designs were alright.

I'm on episode 25 of Liveman and so far I've been powering through to this point. I'm just not feeling this series at all except maybe 2 or 3 episodes. I'm committed for all 49 episodes I just hope this series gets better because these first 24 have been very mediocre for me.

Does watching the opening credits to Sun Vulcan count as watching it??? That tune is catchy FOLLOW THE SUN! CATCH THE SUN! makes me want Sunny D

See, I thought Liveman was excellent and took a dip when the other two rangers showed up for their first 10 or so episodes.

For subbed, go with GekiRanger. Also check out KakuRanger, CarRanger and GoGoV (I think all three are currently being subbed).

Finished Dekaranger after starting it at the end of December, now watching Zyuranger and trying to get caught up with the weekly releases. Currently on episode 7

Yeah I think it dipped a bit when the other two showed up as well. That and the fact Bias could have used some expanding on were really the main two things letting it down.

I just got up to the point in Dekaranger where we first see DekaMaster. I am really loving this show and all the great characters. Even the episodes I think I'll hate - like Umeko and the giant alien baby - still end up being really fun and enjoyable.