I don't know if WCW or TNA truly had a 'prime'. If TNA has a prime, it's probably right now. My heart says if you count JCP era NWA that was a precursor to WCW, then it had two primes. I think mid-90's WCW also counts as a prime. With that being said, even though they had a great midcard and big stars on top, the main event level stuff wasn't always great in-ring and the midcard stuff was but wasn't always booked well. WWE's prime is debatable. If you say Golden Era was the prime, then they suffer from the same problem mid-90's WCW had. If you say New Era was prime, you had bad ratings and next to no name value and some horrible profession based gimmicks, but it might be the height of midcard and main event wrestling quality. Pity hardly anyone watched. Attitude Era was top heavy, but in the best way. They also filled the midcard with OK wrestlers at best, and while there were lots of champions, few belts meant anything. Post-Invasion WWE was a rebuilding phase similar to New Generation, but you still had some lingering stars along with a strong roster fresh out of one of the best OVW classes ever. Big names like Orton, Batista, Brock, and Cena were cultivated. Meanwhile guys like HBK, HHH, and The Undertaker were hitting their peaks and picking up main event slack. While true wrestling lost a lot of it's fan base around that time, WWE kind of kept theirs and built for a stable future. WCW's prime was way more bankable, but also bred bad business and booking habits. TNA's on the mend from being booked poorly for nearly 20 years. It's not what it was, and that's a good thing. I'd say WCW's mid-90's prime wins out for me.