Firstly, the word ‘actually’ gives the impression that you are surprised that you like the idea. As if you were expecting that the proposed idea would not be good.

Another issue with the phrase “I like …” is that it is more about the speaker and less about the idea giver. They are the one who came up with the idea, they should be getting the focus.

A better way would be to say simply, “That’s a great idea! Let’s do it!”