I agree if you scale any of thiese down its going to be a mess, all very busy logos.
I would lose the lightbulb and go with "the thinker pose" and a cabin just two flat vectors without too much detail and negative space.
Perhaps the thinker sitting in front of the cabin.
I know it might be a bit late to give feedback now, but I would stick with no.3. The cabin and light bulb are both incorporated in the logo text. Which makes the logo modern and easy to remember. The light bulb is also a symbol that represents "ideas" and it's perfect that it's there. No.1 and no.2 don't seem to be as modern as no.3 and no.4. The problem with no.4 is that the light bulb is not present.