Amazon RDS t2.small as a production server
T2 instances are given cpu time based on a credit system, and t2.micros are have the least overall cpu capability in the instance class. These credits are accumulated at a rate of 6 per hour on a t2.micro, which gives you the ability to burst to 100% of the cpu core for 6 minutes. All other times you are only granted 10% of the core. Furthermore, you will only accumulate credits if your instance is completely idle.

http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/t2-instances.html

Depending on the purpose on your production server, and how much downtime is acceptable, ... you can always start with a t2.micro, and upgrade the instance if you see that there is need for more resources. Mostly you can upgrade the instance type in 3-5 minutes. Just power off, upgrade type and power on. I think that's more than a reasonable 'maintenance downtime'.