When it was on air, TNG eclipsed TOS. And even afterwards, TNG so friggin' influential on the franchise - and spawned so many spin-offs - that, hell, even DIS qualifies actually more as a TNG spin-off series than a TOS companion series.
There is but one major reason why (currently) TOS is the bigger franchise: It was recently revived with a (mostly) successfull blockbuster franchise.
TNG on the other hand, never managed to capture mainstream success with it's movie series. Domn't get me wrong: I like the TNG movies mostly. But they are hardly as influential, popular or even well-known as the TOS movies.
But here is a very important destinction: This is the current state of the Trek franchise. It's not written in stone - it has changed a lot in the past, and it will change again. If they actually make that new Picard series - then THAT will be the juggernaut of the franchise, easily overshadowing DIS, and probably even the Kelvin timeline movies purely because of the novelty and it being the "new" iteration of the franchise.
This is the beauty about the Trek IP: It's fluid. It suports lots and lots of different versions. It's not like "Battlestar Galactica" or "Lost in Space", which are one single entity, and then always variations or supplements to the one original IP. TNG proved the Star Trek universe itself is as much a playground for new characters and stories that can be equal or even eclipsing the original.
TOS might have been the original "Avengers", in that it started the craze on a whole new level. But TNG was their "Infinity War", where they proved the IP is not limited to the original few characters, but can sustain complete new sets of characters and stories as well, and not lose any of it's appeal or be a pure shadow of the original.
I have to disagree there strongly. I personally don't like the JJverse movies that much. All of them have elements that I truly love, but overall they were a disappointment for me.
But it can't be understated how helpfull they were for Star Trek as a franchise. Yes, they have become stale nowadays as well. But at the time, a whole new generation of audiences was able to see "cool" Star Trek for everyone.
Literally all people I know that are significantly younger than me that are Trek fans - started out by watching the JJTrek movie. That was their gateway drug. They saw it, and if they were interested they realized there is a wealth of material to check out. I don't love those movies. But they are the single reason why many people today are familiar with the whole beaming/starships/shields/phasers on stun/Warpcore-schtick and all the major Trek concepts in the first place.
See, for me, the JJ films didn’t have that impact in those around me that are younger. Voyager did for the now early twenties crowd. Maybe that’s because the films had a rating, rather than being PG. maybe it’s because there’s a money barrier to film releases that doesn’t exist for watching TV trek on whichever channel is showing it. So the splash didn’t look that big to me.
They meant I could get me and my son some starfleet uniforms without being gouged (last Halloween me and him were scotty and Kirk, even before the day, he’s had his Kirk-shirt for years...and we popped mummy and aunty in my older uniforms, so we were all on theme....) and I could buy him a Lego enterprise, even if it had blue Bussards. Relatives cottoned on, and he got a set of action figures...but they lay forgotten while Star Wars does its thing. As it ever was....except when TNG had a toy range. Then those figures were everywhere. In the olden days.
I saw some fan art on Deviantart, but overall, it felt it’s splash damage in geekdom was slightly above Tron Legacy but below pretty much everything else.
I would say STO is driving as many new fans as the movies some days...and that’s...kind of sad in a way.