Oil Paintings have been used by historians of Art like Van Gogh, Leonardo Da Vinci to create the masterpieces like Starry Night and Mona Lisa to name a few. Veteran artists prefer Oil Paints to Acrylics primarily due to the shelf life that use of oil paints gives the painting. The painting created by using Oil paints is generally regarded as Timeless. However, there are certain set-backs that come along when you adopt oil paints for your masterpiece. Oil paints are viscous in nature and need chemicals to manipulate their texture and viscosity. e.g. Turpentine
Acrylic Paintings are popular with beginners who are experimenting with various mediums used for painting. Acrylics have a longer shelf life. The acrylic paintings do not change colours or develop any shady tints. Even after many years, they tend to look just as they would look today. Acrylics are thick paints which can be thinned by water.
Time to Dry a Painting
Oil Paintings take a phenomenal time to dry. Additionally, this is also dependent upon the environmental factors where you are painting like the Humidity, Temperature etc. Acrylics on the other hand are totally opposite in nature when it comes to drying. They can dry within minutes. An artist needs to be super focussed when working with Acrylics as they are quick in drying.
Aging due to Light Exposure
Both the mediums, Oil and Acrylics react very differently when exposed to light for a long duration. You must have seen old and historic paintings which the veterans have created with Oil paints; observe closely and you’ll see a yellow coloured tint developing on the painting. This shows that Oil Paintings fade with time and the exposure to light makes them age and change colours by becoming dull with time. Acrylics have no such behavioural traits. The paintings made by using acrylic colours, stay bright and vivid even after many years.
Flexibility of the Paints
Acrylics are very flexible as a medium. You can easily play with them by adding chemicals that change the behaviour and texture of the paint giving you more freedom to use them as you wish. Some mixers can render very thick acrylic paint texture which can be used for a certain style of painting. Some mixers can increase its drying time which makes them behave more like oils. Acrylics offer the artist an avenue to explore the usage of mixed media.

Oil Paints are more expensive than acrylics. if you are looking for something to suit your budget, opt for acrylics to begin with and then you can slowly upgrade to Oil paints. Artists also need to take some safety precautions when working with Oil Paints as they are generally used along with chemicals like Turpentine or spirit which are toxic.
The choice of a medium to be used for a painting thus depends upon a lot of factors like the forms, textures, speed, effect, longevity involved while creating the masterpiece you want to. Think through, practise and make an informed and experimented decision, whether Oil paints or Acrylic Paints will do justice to your piece of Art.