Paid Fastmail User here since around half a year. Did extensive research on what provider to use and trialed fastmail for four weeks before buying. I went for a 3 year period. Fastmail has a fantastic set of features.
There are providers that are focused more on privacy (e.g. PGP. encryption, not being based in Australia) but that was not my top priority.
I have created a lengthy guide as part of my transition: I published the Markdown file to Fastmail at this link (it is a text file). As it was initially written just for myself, the format might not be very readable :)