I imagine you have got a new driver already, but I will answer your question all the same for future reference of other players. Talent is an important attritbute to consider as it is the only one that cannot be increased through training. At the lower levels, I imagine it does not make much of a difference. But if you are putting up a driver with a talent of 2 up against a driver with a talent of 12, it will probably make a significant difference.
Experience is another one that cannot be increased via training, but this will increase with, you guessed it, experience. This trait will increase after X amount of races.
As far as the other attributes go, stamina is an important one to look at, as this will determine how much a drivers health will deteriorate during a race. You may want to consider wet weather as well, as obviously the higher that is, the better the driver will do in the rain. Apart from that, every driver is going to have their strengths and weaknesses that you can either focus on or ignore via training.
Hope this helps!










