Who is the Strongest Human? This topic has been hotly debated by fans of the series for years now. I think it's time it was laid to rest. In my opinion, Tien is definitely the strongest human in the series. For this editorial I'm choosing the exclude Uub, since he only has his great strength from a wish with the Dragon Balls.
When Tien first entered the series he was definitely strongest human, and stayed that way throughout the rest of the series. If we look at the official power levels written by Akira Toriyama himself, it shows Tien is stronger. Even without that information it's obvious to me that Tien is stronger than Krillin and Yamcha by far. During the 22 nd World Tournament, where he first appears he beats Yamcha with ease, not even breaking a sweat. He then goes on to defeat Goku and with the entire tournament! Since Goku had beaten Krillin and we knew was stronger this proves Tien is stronger than Krillin at this point in time.
During the King Piccolo and 23 rd World Tournament sagas, Tien remains to be superior to Yamcha and Krillin. Seeing how Krillin was easily killed by one of King Piccolo's henchmen it's obvious he wouldn't have stood a chance against the King himself. It is around this time that Goku starts to surpass Tien in strength. When Goku defeats King Piccolo it is only with the help of Tien that he was able to succeed. When the tournament rolls around he easily defeats a cybernetically enhanced version of Mercenary Tao, one of Goku's greatest rivals; and gives Goku a truly amazing rematch in the second round of the tournament.
When the Saiyan Saga comes around there are still power levels that prove Tien is the strongest human. It's after this saga that things change. Since Tien died during the fight with the Saiyans and Krillin did not, Krillin is able to surpass Tien in strength. It's when Krillin meets Guru and receives a power-up does this happen.
However, while Krillin is fighting on Namek, Tien is training hard in the afterlife with a god named King Kai. To say that King Kai's training is excellent is a true understatement. Goku trained with him for a year in the early Saiyan Saga, and his power level literally increased tenfold. All in all, Tien ended up training with King Kai for about an entire year, obviously raising his strength enormously. With this incredibly beneficial form of training, it's quite likely that Tien made up the difference between himself and Krillin caused by Guru's power-up. (And in DB, he seemed to benefit more from training, constantly staying stronger than Krillin, so that information supports this idea.)
Skeptical? Well, although Tien and Krillin's strength are hard to compare during this time, there is one group they both fight at almost the same period of time, this group is known as the Ginyu Force. When Krillin fights them he loses terribly, not even Vegeta or Gohan can measure up to these guys. However, when the Ginyu Force is called by they are invited to King Kai's planet for a fight. It is at this point that we see Tien, Yamcha, and Chiaotzu fight the Ginyu Force. Amazingly, they defeat them with ease; Tien even takes two of them at the same time. This even proves that he's stronger than Vegeta! Well, at least for a short bit of time. Vegeta unlocks an enormous amount of power when he fights Frieza, but that's a different story.
After the fight with Frieza, the Z-fighters go their own separate ways to train for the upcoming battle with the Androids. They train for three years. And once the Androids have arrived, Tien has actually been training almost constantly for the past 4 years!
When the Androids arrive, Yamcha is easily defeated by the weakest of the Androids and, basically gives up on fighting. Krillin appears to be more afraid than ever and Tien much stronger. When Cell surfaces, he has a brief match with Krillin that goes nowhere and eventually absorbs Android #17. At this point Cell's power skyrockets and Tien knows he has to step in or Android #18 will be absorbed as well. Tien uses his most powerful attack, and in my opinion the best attack in all of Dragonball, Z, and GT, the Tri-Beam Cannon. Because of Tien's actions Android #18 was able to escape. However, because of Vegeta's arrogance he allowed Cell to absorb #18. Seeing how Tien's attack was able to stop Cell in his second form, and Krillin could barely do anything on the first form, the inference is quite obvious.
After the final battle with Cell, Krillin retired from fighting and quit training... Tien didn't. He trained in the mountains for seven years. If there had been any distance between them at that point, Tien made it up and easily surpassed it. Not training weakens a fighter dramatically; Gohan went from easily defeating Perfect Cell to barely being able to handle Dabura. Krillin's loss in power was certainly just as drastic, where as, Tien was only gaining even more strength at this point.
During the 25 th World Tournament, Yamcha states that Krillin is the strongest Human, and this has often been used as evidence to prove Krillin's superiority. This, I feel, is wrong. Yamcha merely said that to cheer up Marron, Krillin's daughter. And furthermore, Tien left the group seven years before hand, so they hadn't seen, or even heard from him since then. To add to that, we all know Yamcha isn't the brightest bulb, and has a hard time measuring powers. You can often hear him shouting foolish remarks when watching fights go on.
When Majin Buu arrived, Krillin proved himself to be a nonentity, never even fighting Buu once. Although, there is one case that Krillin battles Kid Buu, but this happens to be filler, which I am choosing to not count.
Towards the end of the saga, Tien arrives to help Gohan fight Buu. At this point Buu had absorbed SSJ3 Gotenks and Piccolo into his being. Buu fires an attack at Mr. Satan and Dende. Fortunately, Tien deflects it. Being able to deflect a blast from the second strongest form of Buu is quite a feat, even Buu remarks on how strong Tien is. By deflecting that blast, Tien saved the lives of Mr. Satan and Dende...and when you consider how vital Satan is to Earth's survival later, as he uses his celebrity status to rally all of Earth to Goku's cause, you realize that Tien saved the word. (And furthermore, by preventing Dende's death, he also prevented the disappearance of the Dragon Balls.)
As you can see, even in the sagas after no official power levels were given out, Tien contributed more to the major battles with his superior strength. But even with all that aside, Tien has a few more impressive accomplishments under his belt than Krillin. For one thing, his enlightenment is so great that the mysterious third eye which all beings supposedly possess materializes physically on him. Additionally, that place on the Human body, according to some Chinese philosophies, is a chakra from which power can be derived. It is safe to say that Tien is a master of this. Tien also has many impressive techniques: The Tri-Beam Cannon, which I described earlier, the 12 Eyes technique, which allows him to replicate himself four times; the Solar Flair, which produces a blinding flash of light and stuns the enemy, a move that once saved Krillin's life; the powerful Dodon Ray, the first energy attack seen in the series outside of the Kamehameha. Tien was even the first to fly in the series, the list goes on.
Still not convinced? Look at the differences in their characters. Tien is a recluse who dedicated his entire life to training and is a serious warrior. Krillin is most often a practical joker and retired from fighting after the battle with Cell so he could settle down and start a family. It's clear who has placed more emphasis on fighting and training, and it's also clear who is stronger for it.
With all this evidence, both empirical and circumstantial, it is difficult to deny Tien's superiority. He is indeed the strongest human in Dragonball, Z, and GT.
