Despite living in the middle of an Arriva area, I rarely find a reason to use their services over the one GNE service we have.

Having said that, when I have used them, other than the presentation of some vehicles, and the quality of some drivers (although that seems to have improved vastly, a few years back I remember having a driver who literally couldn't speak a word of English! How they got the job I'll never know), I don't really have a problem with the service. For the most part they turn up on time and get me where I need to be.

And if there's a delay, THE APP ACTUALLY TELLS ME! It doesn't cover it up and just change the time without saying anything like the GNE app does. If I need to make a connection, I NEED to know it's running late!

As for Stagecoach, of the very few times I've used them (I can only recall using them maybe twice in the last decade), I can't say I was impressed. The drivers were shocking and the buses weren't much better. But, due to the small sample size, I can't really make a valid assessment of them either way!

In my experience of GNE and Arriva, I'd probably say Arriva offers the better bus service, but I'd definitely say GNE offers the best 'experience' (if they turn up).
I don't believe that GNE have any truly 'bad' buses left (although I'm happy to be corrected on that), whereas Arriva definitely do have some shockers out and about!