What is the current security level of an algorithm?
First of all: The security and the length of the key depends on the system you use. So e.g. RSA needs longer keys than AES-256 does, to ensure the same security.

Second: The level of security depends on the application and how secure it has to be. A important point here is: How long should it be secure. There are still security systems in use, that can be broken in days. That's however no problem when the information only has to be secure for some minutes/hours.

This question / answer about algorithms used for SSH keys on the Information Security site might also help you.