the one of them you said, 것 같다. is better one. and you can also use -라, -다고 느껴. ex)아니라고 느껴. 많다고 느껴. and there are some more natural expressions. -듯 싶어. ex) 네가 틀린 듯 싶어. I feel like you're wrong. (when you feel but you are not sure, you can choose this.)