Bootstrapped with 1000 paying users OR viral app with 1M non-paying users?

It's easier to know how you're doing when you charge money. If you have 10 paying customers you're not doing well. If you have 100k free users you probably won't know how you're doing, you may need them to some specific behavior or need larger numbers to make your thing work.

I wouldn't pick one because you think it will be easier than the other. It's safer to assume they'll both be really hard, but probably in different ways.

I'd go with the first one. You can make it scale with other ideas later on or with new products, and you'll have a solid base to work off of. The viral app idea is a crapshoot these days.

Thanks. That is what I am leaning towards as well.

Well, with the first one you'd make money and do less tech support.

Paying customers are (rightly) far more demanding.