Which rolex holds its value ?

In general a Rolex watches hold there value.  But not every Rolex model has the potential increase a lot in price.  Certain model lines of Rolex watches are more passionately collected than others, and can have much greater chances of appreciating in value. The production numbers of vintage Rolex watches are fixed and a lot less then nowadays, but the demand only increases.

Wil Rolex prices come down ?

No, Rolex watches are in general a  good investment, but not every Rolex watch has the potential to be worth more than a new one simply because it is old. Certain model lines of Rolex watches are more passionately collected than others, and can have much greater chances of appreciating in value. Often Rolex not only holds its value but will also increase in price, but it is the vintage market where all of the record-breaking valuations occur. The production numbers of vintage Rolex watches are fixed and a lot less then nowadays, but the demand only increases.

Why is Rolex so populair ?

Rolex watches are known for precision, high-quality, prestige, and luxury.  Rolex has a long history as luxury brand, and prices are always increasing.

Should i buy a Rolex without serial number ?

No, in some cases these watches are stolen. Serial number are damaged, so the watch is not traceable anymore.
In some cases you see vintage Rolex watches damaged serial numbers caused by the endlinks on the bracelet.

Does covid 19 / corona virus effect the prices on the Rolex vintage market ?

The prices of vintage watches are very stable. In general vintage / second hand Rolex watches are cheaper than new models and follow the yearly price increases. Because of the large interest in classic rolex watches and the limited amount available the prices will increase with the prices of new Rolex models.