I started on one of the smaller instances, and guess what? They didn’t make it. I spent about two days setting up my account searching for all the communities I wanted, and had a great feed. Then about a week later, they were gone. I can’t fault the admin- they were doing a lot of work and running up a server bill largely for gratis, but I lost all that setup time. So when I had to start a new account I chose to go to one of the moderately large instances because I didn’t want it to go poof overnight again.
What I’m saying is there is safety in the medium to large instances.
That said, I do have some problems with some of the largest instances throwing their weight around in performing global bans on users from other instances whose world views differ from theirs.