Tools and settings for compressing x264?

[NeonBible]

I still don't have a BD burner and I have gathered a few fan projects which sit on my backup HDD. They are around 20-25gb each.

I tend to have a smaller portable HDD for watching media on my TV. I would like to compress some of these videos with optimal settings.

I am looking at settings to convert a 1080p down to around 8gb. And also settings to go down to 720p at around 4gb. Both of these are excluding audio which I will leave completely untouched.

FFmpeg would be the tool for the job right? What commands might I use to achieve the above at the best video quality?

[MrBrown]

I mostly use Handbrake or RipBot. Both Tools are free and do nice jobs.
I recommend to test some Settings, because whats good with one movie, sometimes not really works with another.
I think with RipBot you can set the filesize, and the Bitrate will be calculated automatically.

And it depends on the Audio streams you want to have and use. An Atmos 9.1 Track unaltered will use more space than an ac3 2.0 192kbps Stereo track... obviously.