There is no best class or race, the best builds are the ones with the most synergy between all the individual components.
To answer your question in the most relevant way for a new player about to roll their first character though, IMO Imperial is never a bad choice and is the most flexible choice for every class except maybe Sorc.
If you're not rolling Imperial, each class has racial options that are just as strong but may or may not be as flexible.
Altmer for Sorc.
Dunmer for DK
Bosmer for stamina NB.
Breton for magicka Templar.