As a general inquiry I would use:
- ¿Qué tal (fue/estuvo/anduvo) tu día?
- ¿Cómo estuvo/anduvo tu día?
Note how estar and andar work in the same way here, and sometimes ser as well. In the second example I wouldn't use ser because ¿Cómo fue tu día? sounds like you're asking for a description.
These two can also be used but they may have different connotations:
- ¿Cómo te fue hoy? (sometimes suggests the other person had some important task or appointment ahead today, and you're asking how that went)
- ¿Cómo estuviste/anduviste hoy? (sometimes suggests the other person had some ongoing trouble, such as an illness, and you're asking how they've been feeling)
You can sometimes substitute el día de hoy for hoy, but that sounds a bit more formal. In some places in Latin America people say hoy día (almost as a single word) for hoy.