No actually, it all depends on what kind of fight you are going to do.
If you are going to do a few quickies. Then leave, Your best bet is either Gohan, or trunks, because they transform fast. They are also good for training because they are slow.
If you are going to Have a long fight, most would think Trunks is best in the long run, because he transforms the fastest. But in the long run, he isnt' the way to go. Because a saiyan's pl multiplyer is by 2x everyone elses is 1.5. So if you are vegeta you come out of top in both speed and strenth, It's his beams that he lacks. The only one he can move with is the Gallit Gun, but that is not as strong as the big bang attack or the final flash. If you are Goku then you are probably the most forunate, because he starts out at a decent PL, his transformation level isn't too bad. His speed is the same as vegeta's. And he can move with all beam attacks. And can even teleport. (now he can teleport with the generic beam, i find that very usefull)
Cell is good because he starts out fast (as fast as buu) has a great pl starting point, and a good transformation point. Although in his transformed state he gets the gallit gun not the kkh, which i believe on cells part is a down fall.
Buu is probably the best character to be if you want to win a match. One, he is the strongest. 2 he is as fast as cell (cell and buu are the fastest) 3. He has the candy beam, if you win with that you can heal yourself and get more pl. He can regenerate at 1 hp/s. His mouth blast, is by far the best beam thiere is. It is powerful, and you have a lot of control over it. Probably just as much as a generic beam.
Krilling... he becomes the fastest at trans. But other then that he sucks. He has the khh, which is good. And the scatter beam which is good if your not paying attention, other then that he is pretty much worthless, unless he is transformed.
I think i forgot someone.... But i'm not sure. If i did i will come back and edit this.