Here's my self-serving advice for every one-man SaaS:
Use Heroku.
It's super easy to get started. And when you reach $2000+ in monthly bills, hire me to move things over onto dedicated or EC2 so that you'll get 10x that performance for the same price.
As for the actual language, I think PostgreSQL + Ruby Backend + JS Frontend is still the easiest way to get started.
All those great architectural ideas don't matter much until you have your first $5k monthly in reliable revenue. And by then, you'll have a completely different perspective than what you think you need now.
Use Heroku.
It's super easy to get started. And when you reach $2000+ in monthly bills, hire me to move things over onto dedicated or EC2 so that you'll get 10x that performance for the same price.
As for the actual language, I think PostgreSQL + Ruby Backend + JS Frontend is still the easiest way to get started.
All those great architectural ideas don't matter much until you have your first $5k monthly in reliable revenue. And by then, you'll have a completely different perspective than what you think you need now.