The PPV's started in 1997. Hardcore TV or some form of it dates back to 1993.
Unless you're talking about the big shows ECW held, which had a PPV feel. If you're talking about, for example, shows like Heatwave '96 or Return Of The Funker in 1995, you would probably be better off watching those shows/PPV's, since Hardcore TV was usually 2 or 3 matches for the most recent event, with a bunch of promos, vignettes and ECW hawking the shit out of merchandise and VHS.
At least then, you have the potential to see every match, although Hardcore TV was pretty good for hyping events, as well as providing a backstory on whatever was happening at the time.
I guess it all depends on what you're looking for, where you actually want to start watching from and whether or not you solely want the wrestling aspect or if you'd like to see entire angles.
The supercards. Hardcore TV was basically a recap of that. ECW would average only about 4-5 shows a month, prior to getting PPV. 2 supercards and the rest in house shows. Hardcore TV contained footage from those events, with the only difference being less matches (and some that made Hardcore TV would be clipped) and the addition of promos and detailed recaps of specific feuds/angles, such as Stevie Richards wrestling as Stevie The Body/Stevie Flamingo/Stevie Polo (which prompted the debut of Raven), Shane Douglas/The Pitbulls and Taz/Sabu, to name a few.
But yeah, really better off watching the supercards because then, you see everything that would be recapped on Hardcore TV.
It was like the WWF was when it started. An infomercial for live events, where the actual events of the promotion were taking place. Wrestling as a TV serial drama is a relatively recent thing.
The only way to experience it is first hand when it comes to ECW and WWF if you want a complete viewing of what these promotions actually put out. Those Collesium home videos are likely long gone which featured exclusive content to them. ECW didn't tape every event and put it on VHS.
"Local" TV show with a fraction of the matches plus whatever else is available for sale, meaning everything, is the only way to go when "reliving" an era of wrestling. It would be absurd to only watch Raw or Smackdown in the AE, and likewise, it makes no sense to ignore the flashship and for most of it's run only TV show ECW had. I never missed it once I started to watch it. It felt like they discussed and showed enough of the angles to work, even if it was far less than what they did.
That's why I'm not watching wrestling 24/7. Give me all the shows that came on in an era on demand or shown in the right sequence and I would watch nothing but wrestling. But it's like only listening to a bands greatest hits CD when you grew up with all the albums. ECW is a lucky exception because they had one show per week that people loved enough to archive.
I would be shocked if the complete run of WWF Mania! existed, but having seen it when it was on, realizing it was a worthwhile component of the product or not seeing There's hours and hours of segments featuring raven and gorilla that no one gets to see anymore too. ECW doesn't have this problem and benefits for it.