Multiple web frameworks in single AWS instance?

This is an infrastructure design question. Is it better to:

1. Run multiple web frameworks on a single AWS instance?
2. Run each framework in separate AWS instances?

Here are the web frameworks used:

• Backend: Django + PostgreSQL
• Frontend: NodeJS
• Forum: Ruby on Rails + PostgreSQL

Option 1 pros:

• No need to worry about AWS instance type (just use a powerful one)
• Easy to maintain when everything is in one place, only 1 instance

Option 2 pros:

• Better allocation of AWS resources depending on load (backend / frontend / forum). Easier to scale?

I am not sure what's the better option. Would love to hear your experience and opinion on this. Thanks.