Most creative Ki techniques?

[Future Warrior]

This can span to pretty much all DB material.

 

[SSJ2]

 

[Captain Cadaver]

Gotenks' moves in general are ones that come to mind. The Galactic Donuts being able to trap an opponent makes them a useful distraction, the Super Kamikaze Ghost Attack features both the comedic elements Toriyama enjoys whilst making for a deadly technique and the Boo Boo Volleyball is quite OP when it shows Gotenks has some transmutation abilities, which is kind of fitting when it's used to combat someone who's main gimmick is altering the physical composition of himself and others.

 

[Future Warrior]

Slug did it better.

 

[SSJ2]

Not sure how I forgot this...

Spoiler

 

[SSJ2]

Seriously though, I always found the underwater Kamehameha to be an extremely creative technique.

Spoiler

 

[Captain Cadaver]

^I would've given the underwater Kamehameha a mention too, as well as things such as the bending Kamehameha or the version used with the feet, though it does call into question how much recognition we can give to creativity of the technique itself over the creativity of its user in general.

 

[Future Warrior]

Ki attacks that aren't the conventional energy beams is what I mean by creative.

For example, I think Kunshi's ki generated strings that explode on contact deserves praise.

Spoiler

 

[Spiral-Force]

The Psycho Threads from Bojack Unbound are worth a mention. In a fight against a comparable or moderately stronger opponent, it's a clever way of restricting them so that they can take a beating or drain their own energy by trying to escape. They're also hard to pinpoint due to being so thin and not always visible.