Breakfast

In the whole day,the best imporant is the breakfast.

The most important meal is breakfast. 

Only the reasonable collocation can provide nutrition for the body.

A balanced meal can provide nutrition to the body. 
Sandwich and coffee were my favorite breakfast.

Sandwiches and cofee are my favorites.

The hums and chicken in the sandwich were my favorite.

Chicken sandwiches are my most favorite sandwich.

If have some fruits is better.

All goes well if I have some fruits in addition.

Of course,bread and milk were the good of choice.

Bread and milk are probably the best choices.
But not such collocation every morning.

But I would prefer not to eat the same thing each day.

Sometimes,the time is tight.

Sometimes, I don't have enough time.

I also to eat instant noodles.

 I also eat instant noodles.

Although the reasonable is not good,but the taste was very good!

Although their nutrition is not great, noodles taste great.

Breakfast

In Of the whole day, the best imporant is the breakfast.Only the reasonable collocation (a balanced meal?) can provide nutrition for the body.
Sandwiches and coffee were (are?) my favorite breakfast foods.The hums (?) and chicken in the sandwich Chicken sandwiches are my favorite. were my favorite.If I have some fruits it is better.Of course,bread and milk were are the food of choice.
But I do not always have proper nutrition not such collocation every morning.Sometimes,the time is tight.I also like to eat instant noodles.Although the reasonable nutrition is not good,but the taste is was very good!

"Reasonable collocation" doen't mean anything; I'm guessing you mean something like a balanced meal. Otherwise, good job. Breakfast is important, but it's not always the most well regarded.