I only worked out hardcore for about two months in my life. But I was strict with it and had a steady plan. I would not call myself an expert on the subject, but I do have that little experience and my plan worked for me.
Personally, I liked free weights a ton more. But then again, I only had free weights in my basement. I did not have any machines. I hate working out at gyms. But even at gyms, I favored free weights. I was more disciplined with them, and I saw better results.
I never used a spotter with free weights though. I knew my limits and I was safe. Perhaps it's a dumb move, but my plan was effective, and I didn't do anything unsafe.
I use both but machine is definitely on the lower end but if i had a choice
Free weights you can use stabilizer muscle that you dont use with machines, Machines follow a track built for it so sometimes the movement can feel unnatural, Weight are incremented on machines (unless they are plate loaded)
Mostly free weights, for reasons we all know ( more of a work out to stabilize while lifting, etc.) but I sometime use machines, just depending on the exercise. Mostly upperbody I do free weights, but for example legs I tend to use more machines because my knees are S-H-O-T and I just can't squat with them so I gotta use machines
A combination. I much prefer free weights for upper body lifts (outside of pec flyes - don't trust my shoulder after injuring the joint a few years ago) but machine lifts for lower body for the most part (although I do use free weights - I just feel safer on a machine for the purpose of exercising).
I classify those as free weights. Some movements just are better done on a machine, and in general, free weight machines allow you to customize your workout and workout style (for free weight and/or overhead cabled machines).