Both products trade predictable performance and support for predictable, low, pricing.
However DigitalOcean is a much slicker product. It's both more capable due to the wider range of services, and simpler due to not having all the AWS cruft. It's still not really appropriate for big services (we had outages due to poor DO network management, poor support), but great for what it is.
The attack only lasted a couple minutes and I was able to weather the storm just fine. I only used it as an IRC bouncer. During the attack, my IRC ping went up, but nothing crashed until I got disconnected, couldn't reconnect, and had an e-mail in my box from DO saying they took my droplet down to protect their network.
So, I'd never put a production machine for a business with an active user base there, but... new machines on day 1 of a startup? Sure, it's dead simple. We also had good success with it providing on-demand VMs for developer use, AWS/GCP was somewhat locked down, cost managed, etc, but the team all had a login for DO and could spin up VMs for one-off jobs, that worked well.
As long as you don't use it to "avoid data fees" which seems to be deliberately vague.
AWS doesn't want people putting their apps behind LightSail instances solely for the purpose of reducing data egress costs. I think it's a very reasonable rule considering the situation they put themselves in.
The problem of course is it quickly leads to bad faith instances of people doing just that, then claiming not to be doing it. But it's going to be impossible for them to write a lawyer-proof rule that prevents it while also not preventing legitimate usage.
Like, if I run a web app that accepts requests to example.com/mybucket/myfile.zip, and the app merely pulls myfile.zip from the mybucket S3 bucket and sends it, then yeah, that's a pretty cut-and-dry case of using LightSail to avoid egress fees from S3.
But what if I'm using a LightSail instance as just a load balancer in front of EC2, because I don't think an ELB/ALB is flexible enough? That starts to be a bit more of a grey area.