So, what do you think? I've been an NBA fan since the 80's and grow up in SoCal so followed Magic and the Lakers. (Although I migrated to the Clippers during the Shaq/Kobe era). The popular opinion among older fans is that "it was much better back in the day", which is not unique to NBA basketball but pretty much applies to anything someone grows up with (music, movies, work ethic, etc..., etc....) so that isn't compelling or surprising.
1) Simply naming HOF players from the past, and using this to back up that the NBA used to be more competitive. There can be no HOF players in the current NBA, just as Magic, Bird, Barkley, etc... weren't HOFers when they were in the NBA.
2) Not realizing that total wins/losses are always the same, regardless of the quality of a league. I have heard some argue "there used to better teams, without these weaker teams". Well, for every team that wins another game in a season, another team must lose another game. Seems easy to see, but there are sports sites were some fans fail to grasp this. So wins/losses cannot be an argument for the quality of a league.
My opinion for the argument that today's NBA is better than ever: athletes are evolving because training/coaching/conditioning/films/statistics have evolved. There are simply so many more tools in a team's disposal that was not true 20-30 years ago. Players are stronger, faster, better coached, better conditioned than ever. The arguement that players used to play more minutes and today's NBA athletes are weak and pampered, consider this weightlifting analogy: the stronger and more explosive you are, the more you need to rest. A weak dude can get into the gym and do sets after sets with little rest because they're not moving any weight. A strong, conditioned athlete can do heavy, explosive sets of cleans, etc...which require so much force and power, they need to rest. Look at what Russell Westbrook and Lebron can do, and how they're too exhausted to play back to back days. Now go to your local YMCA and watch unathletic dudes play for hours straight every day of the week.
My opinion for the NBA of the 80's/90's being superior: Players weren't drafted at 19 years old and have only potential. They were more fundamentally sound when they entered the league. The league was still more of a pure game rather than the entertainment, huge money industry it has become. Michael Jordan played in this era and will always be the pinnacle of an NBA player, and pretty much anyone that argues otherwise isn't taken seriously.