I wish to address the superior sulcus hollowing. Which is safer and gives better result? (Photo)

The most efficient treatment for upper eyelid hollowness is filler injection. I have published on this exact treatment and you will find the manuscript on my website link below. Skype consult available.

Superior sulcus hollowing occurs due to volume loss. 
You are right to suggest that your options include filler and fat grafting. 
Filler is a non surgical option and is effective with results lasting up to a year. There is a risk of blindness, so it is best to find an expert filler injector who is well versed with the microcannula technique to reduce your risk.
Fat grafting is operator dependent and carries other risks. Results will be more lasting. 

Superior eyelid hollowing can be corrected with dermal filler injection using a microcannula. This is an advanced technique and so I recommend you have the treatment done my an experienced injector. 

Fat grafting and filler are both good options in the hands of an experienced injector or surgeon who understands the anatomy of the upper eyelid. Your concerns about blindness are legitimate because the blood vessels that supply the eye can be injured during injection. Either fat or filler can occlude (block off) these blood vessels and lead to bad outcomes. Some of the ways to avoid these adverse effects are 1) choose a good injector! 2) use blunt cannulas instead of sharp needles to inject, and above all, KNOW THE ANATOMY. 
Research has been done by prominent plastic surgeons showing that filler actually lasts longer in this area than fat. In fact, filler in this area can last several years and can be diluted or injected in a more precise and controlled manner than fat. 
I hope this helps! -Dr. Leong

The cause of the superior sulcus hollowing is eyebrows repose to the eyelid ptosis. This can be treated with fillers or fat grafting. Fat will give better results and more lasting. The other option is repair of the ptosis which requires in person examination.