Más vale que nunca. temprano rico tarde mejor

This is a common saying in the Spanish speaking world. Recall that a saying is a short, pithy expression generally containing advice or wisdom. So this phrase means in English better late than never and means that you arrive or do something later than expected and this is not good, but it's better than not at all. This phrase is often expressed with sarcasm saying something positive but remarking on someone's lateness. So:

Más vale tarde que nunca.

this question is given using the conditional form. conditional tenses are is used when talking about hypothetical situations and probabilities. also, this is used when making polite requests. so comprarías is the conjugation of the verb comprar that matches the second person singular in the conditional. finally:

¿cuál comprarías tú?