Best SFF video card?

Solution

That's not a half-hight low profile card though, which they seem to be looking for.

Currently, a 1050 Ti is the best that you're currently going to get in that form factor. Nvidia should be launching a new generation of cards within the next few months or so, but there's no telling how much longer it will be for new lower end parts will come out, or if they will manage to fit any more performance into that form factor.
I think you won't find anything higher as it would need to have additional power and most sff PSU's won't give as much juice.
at 75W of power 1050 TI is strongest one without juice cables. Also heat problem is a major drawback.
have you seen zotac MAGNUS EK71080 ? I think they made custom water cooling to insert 1080 inside this little monster.

update:
looks like they did not, but laptop(low power) i7 + a lot of magic done here.
 

That's not a half-hight low profile card though, which they seem to be looking for.

Currently, a 1050 Ti is the best that you're currently going to get in that form factor. Nvidia should be launching a new generation of cards within the next few months or so, but there's no telling how much longer it will be for new lower end parts will come out, or if they will manage to fit any more performance into that form factor.
 
Solution
If you want more powerful cards. You can always just get a larger case. Even a cheap $25 one is fine. After all they are just metal boxes with mount points. More creative people build something out of wood or cardboard to save more money.

You'll also most likely need a better PSU as SFF have weak PSU in general.
 
Thanks for your answers everyone. The card is for a desktop given to me from my buddy who died of cancer last year. I just want to upgrade the PC he gave me. I already have a desktop with a 1080 ti in it, I've just never upgraded a SFF before. Thanks again. :)