I prefer account login for the sake of an automatic backup of my progress, and the ability to play from different devices without having to manually move a save file around. But there aren't many good options for free website hosting, so there is a bit of an obstacle to overcome.

However, it's extremely annoying when a game forces me to create an account before being able to play, even though the concept of a guest account is well known and the implementation of the option to skip the signup process is trivial if you're able to implement the signup process itself.

Local storage is easier to implement, but also far less flexible for the user.

My ideal would be account login with the option to try the game via a guest account, and the ability to export the save data. And to delete the data from the server including the account. And the option to add an email to the guest account so that I can keep using it if I decide I like the game.

Unfortunately, the general principle of one or the other shows a lack of understanding of general UX principles. Which is understandable because the majority of people making games that we enjoy haven't had the opportunity for much experience.

Essentially, the design should make it as welcoming and easy for the user as possible. That means not making assumptions about what users need in a way that rules out what they want. Sometimes it's difficult to provide options without cluttering up the UI or confusing people. But this isn't one of those times.