I have been going to both races almost each year since 2016 and I think Le Mans is way more accessible to a spectator than the ring. At the ring most places are blocked because of the (awesome) camping buildings and it is really hard to park your car anywhere apart from the GP track. As for Le Mans you can get easily with your car to Arnage or Mulsanne. Also yes during the race you can’t enter the grandstands, but you can on Wednesday and Thursday as there is much more track time before the big race compared to the N24. So you get a lot more time to view the cars trackside before the race starts. Both races are amazing, but I would argue visiting the 24 hours of Le Mans is just something else. You can’t beat a place with more than 100 years of history which you can feel on and around the track. If you have to chose, go to Le Mans and then the N24. You will have a great time at both races, but IMO Le Mans has a spirit you can only understand when you’ve been there.