idiom request for "classic is good"

What about:

You can't go wrong with classic, as a general statement. It could be used in sentences like:

• you cant't go wrong with a classic suit, or a classic restaurant. It depends on the context you have in mind.

They don't make them how they used to.

Your comment is really key to any meaningful answer:

...the real context is my girlfriend bought a new pair of shoes and said that they are too classic and boring. And I wanted to tell that "Classic is best"...

So the real question here is one of following the latest trends vs. maintaining a timeless classic style.

While not exactly an idiom, the most famous quote related to this would be

Fashion passes; style remains

which has been bastardized several ways in modern times:

Fashions come and go, but style goes on forever.

and

Fashions fade, style is eternal.

"It's a classic for a reason!"