TNA, imo, started getting good around 2005. As you're an old school WCW fan like me, you'd probably find the earlier years interesting, as there's a lot of WCW alumni plying their trade in TNA during that period, but pretty much all of them are a shadow of what they once were. You'd be watching it more to just laugh at the classic 'LOLTNA' stuff, of which there was plenty during 2002-2004. It's a fascinating time capsule, and there
is some great wrestling in there, but are they great shows in general? No.
2005, TNA starts cooking. The PPVs in particular are a lot of fun. The weekly shows are still a bit hit and miss. 2006 - 2007 I would say is TNA at its best. I really enjoyed watching it back then. A ton of fantastic young talent, mixed in with just the right amount of veterans. I remember Christian, Angle, Tomko, Sting, LAX, AJ, Daniels, Joe, Monty Brown, Booker T, Abyss, Team Canada... almost everyone just going out there and killing it. Even the older guys like Nash and the Dudleys found ways to be entertaining, and they had Cornette and Zybszko as authority figures for a while as well. The booking could still be quite bizarre at times, but I'm okay with that. It's not like WCW's booking was consistency logical either. 2008 is still a strong year, but more focus starts to go onto the older stars. You get the rise of the Main Event Mafia later in the year (Angle, Sting, Nash, Steiner, Booker T) which dominates the main event scene in terms of storylines for some time. 2009 isn't bad either, although I felt like TNA was getting to a crossroads where they needed to decide whether they were going to keep coasting on the reputations of old stars, or begin elevating their own homegrown talents to the next level.
It all goes to shit from 2010 onwards. Hogan and Bischoff come in and whilst it's entertaining in a car crash kind of way, the show went downhill rapidly and TNA never really recovered. The younger stars mostly got buried in favour of Hogan's boys and pretty much anyone WWE was releasing at the time. They moved from six sides to four, which hurt the brand. Just generally lost what made them unique and became WWE-lite. For whatever reason I did keep watching (more out of habit than anything), and honestly, I do remember kind of liking the Aces & Eights storyline when it first started. TNA found a groove of sorts between 2012-2013, but the company was haemoraging money and production was falling off a cliff. Booking got really bad again around mid-2013 and once AJ left, so did I.
So, my advice would be 2006-2009 for sure, 2005 as well if you want to stretch it a bit further. Just watching the PPVs from 2005 would probably be fine though. The only show that's worth watching past that is the Jan 4, 2010 Impact - which was the first time they went head-to-head with WWE on Mondays. It's an unstructured, chaotic mess of a show that was a sign of bad things to come, but still fun to watch.
Archive.org has all of the TNA shows from 2005 - 2009:
2005 -https://archive.org/details/tna-i-mpact-2005.11.03
2006 -https://archive.org/details/tna-i-mpact-2006.11.16
2007 -https://archive.org/details/tna-i-mpact-2007.10.04
2008 -https://archive.org/details/tna-i-mpact-2008.03.27
2009 -https://archive.org/details/tna-i-mpact-2009.02.05
I don't think the PPVs will be on there, but you could probably find those on the tracker? Speaking of which, if you ever get an invite to throw out, give your boy a holla
