Anything down to a t2.nano should be capable of many megabits, it's TCP latency or routing that will slow it down. My t2.micro instance can generate 50MB/sec internally within AWS to another instance. I just had a play with FTP and got 15Mbps (2MBps) up to that t2.micro instance over a Vodafone corporate fiber connection. If I tested from a computer in the USA I would expect it would go a fair bit faster.

Vodafone routing is often  non-optimal. That's part of the reason I moved to Snap/2degrees.