I choose chakra. Ki would make taking over the world way too easy. Chakra would make it more of a challenge and therefore more fun. The question is really what jutsu we get if we pick chakra. Could we get, say, the Byakugan or Sharingan?
Goku would win. Sasuke has genjutsu, but genjutsu is the manipulation of chakra flow in one's brain to distort the sensory. Dragon Ball characters have ki. And there are distinct differences between Ki and Chakra. Ki requires charging up, it exists in pure energy and needs to be charged before released fully. Using all of your Ki does not end your life, as Ki is not connected to your life force like chakra is. Chakra on the other hand has natures and is directly connected to one's life force. If someone runs out of chakra, they will die. Chakra can be divided and manipulated in more potent ways then ki, being used to create, reshape, destroy, etc. So under the assumption sasuke starts his fight with the sharingan with the intent of using a genjutsu the second he sees the next person he sees, it would have no effect on goku. People in his universe do not possess chakra and ones ki can't be manipulated to manipulate the senses of an individual anyways. There is no conversion, they are different forces. Then it goes to power. The ultimate shield is flawed. Tsunade could Crack through madaras susanoo at one point in the manga and before anyone says omg sasuke is so much better then madara, by how much do you figure? A multiple of 50? Susanoo is a cloak comprised of one's chakra, and madaras was pierced by physical strength. Sasuke can run out of chakra, and gokus natural strength without ssj transformations is leagues above tsunades best. Physical strength wise and speed wise, no naruto character can compete with a dragonball character. amaterasu has a chance of killing goku, but if both characters are fighting to kill, goku would get hit by amertarasu underestimating his opponent at first, rip off the limb/article of clothing effected, and note to stay out of site of his eyes/black flames, which as we see with itachi v sasuke, can be dodge. If playing to kill after dodging amerterasu, sasukes only damaging move, goku could instant transmission and then kill, or simply move faster then the speed of sound and then kill. Hell, doesn't his base travel at like 1.2 times the speed of light or something crazy like that? Anyways, too fast for sasuke to dodge or Consider dodging. Game set and match.
There's way more chakra abilities out there. Some individuals have hundreds of jutsu, in multiple schools of jutsu.
Ki's got all kinds of raw power, but most of the applications end up pretty similar (none of the beam moves are particularly better than eahc other). And/or not that useful (cloning with Ki is normally a disadvantage, for example).
Piccolo KI makes him matter manipulate/control matter. He can create.
KI has allowed people to
Control time
Stop time
Telekinesis
Telepathy
Super strength
Speed
Invulnerability
Disappear
See the future
Turn people to stone
Turn people to candy
Absorption
Fly
Create clones with their own personality
Create solar energy fr the body
hypnotize
Grow to tremendous heights.
Give people powers
Take away abilities.
Transform
Create force fields
Switch bodies with others.
The list goes on and on and on. KI is as versatile ad Chakra if you think everything a DBZ character has done with said abilities.
Note that DBZ characters sometimes have magic or psychics outside of ki, or physical powers innate to their biology.
Transformation is a species specific ability- ki alone won't do it. Absorption is a Buu thing and a cell thing. Control/stop time is a unique ability to an individual. Etc..
Though it is probably worth noting if you do have such an ability, Ki probably makes it better.