I had to go private over 20 years ago when my dentist decided to take private patients only and it was impossible to find an NHS dentist at the time, so I have the same dentist I had before.
I am on a dental plan which means I pay a monthly sum... the amount paid is based on the state of your teeth and how well you look after them. I get 3 appointments a year, a dental check up every 8 months and a hygienist appointment every 8 months. I don't have to pay for those, I don't pay for fillings, I had root canal treatment a few months ago and I didn't have to pay any more for that, and I pay a vastly reduced fee for dental prostheses, crowns etc. For instance, I have just had a crown fitted, it cost me £182. If I had paid the whole amount of the private fee that would have been around £900, the NHS fee is now £326.70. My temporary crown came off and I was able to get an appointment to have it restuck the same day.
I'm waiting for the roots of 2 baby teeth to be removed at hospital on the NHS, (I am on some medication which presents a risk to dental surgery) and then I'm going to have a bridge fitted, and although there will be a significant cost, I am not so worried about it that it would put me off having it.
My husband has a very good NHS dentist. He has extremely bad teeth due to having had a very bad dental phobia before he met me and has needed a lot of work. He definitely had to pay more than me in dental fees in an average year than I did in dental insurance (mine will be more this year). It is usually easier for me to get an emergency appointment than for him. Conversely, I have to arrange my regular appointments at least 4 months in advance, quite often more than that, and he doesn't usually need to arrange his quite as far in advance. We both get excellent care, with local anaesthetic injections if wanted or needed, respect, kindness etc.
My dentist does try to upsell additional services (his practice also has a nutritionist, a sleep service etc) but is never pushy. His dentist has no additional services to upsell.
All in all, I am very happy with my private dentist and with the amount I pay for the service, but I think I would also be quite happy to go to his dentist. I do think he's lucky with his dentist though, NHS dentists are in such demand it is easy for the less 'good' dentists to stay in practice.