HA is safer in my opinion.
I think
FFT is more risky than either
Ellanse or
PMMA.
I've never known anyone who got lumps from
FFT be less bothered about them than from
Ellanse or
PMMA. If you get an infection with
FFT, I don't see how it's less of a problem that with
PMMA or
Ellanse. I've know of guys suffer from impotence as a result of
FFT infections. Guys have died having
FFT. Obviously those serious complications are very rare, but they do exist.
If you have an issue with
FFT and it doesn't respond to the usual therapies, such as steroid injections or antibiotics, the resolution is
Removal surgery. This is the same surgery needed to remove
PMMA or
Ellanse. I know as I've had it. I had the same procedure to remove fat, that @Toothman had to remove
PMMA. We both suffered complications as a result.
I'm not saying not to get
FFT, if it appeals to you. But I'm just pointing out, than in terms of safety, it doesn't belong in the same category as
HA. Of the 4 options you listed,
FFT is the least safe in my opinion. However, compared to other surgical methods, it's arguably the safest.