What are the advantages/disadvantages of each one? I am a little lost here.
What are your requirements? I can recommend to you a Toyota Corolla or a F150 pickup truck but without any knowledge what you need there won't be good answers. Some startups are blogs, others combine several third-party APIs and yet others are very data intensive.
(I'm running AWS, Linode, DigitalOcean, bare metal server myself, all depends on what the project needs).
Also if you are leaning more towards Digital Ocean, do consider Linode. I prefer Linode.