PLA


Printing:

PLA or to use it's full name, Poly Lactic Acid is probably the best material to get started with when you first start 3D printing. With the help of the 3D printer's onboard fan it will cool and set very quickly. This means that you can avoid warping and achieve a range of shapes than would be difficult with other materials.
Finishing:.

After 3D printing you can finish your model by sanding and spraying with automotive spray filler. You can also paint directly onto PLA with acrylic paints.
Environment:

PLA is kinder to the environment that other plastics as it is derived from corn starch and not fossil fuels. It is also biodegrade in an active compost heap.
ABS

Printing:

ABS, or Acrylonitrile Butadiene Styrene is popular in industry, being used for products such as car bumpers and LEGO® due to its toughness and strength. ABS is probably the second easiest material to 3D print with, but care must be taken when printing larger objects as it can suffer warping as the 3D model cools.
Finishing:

ABS can be finished by sanding, spraying with automotive spray filler and using Methyl Ethyl Ketone as a solvent. You can also paint directly onto ABS with acrylic paints.
Environment:

ABS is produced from fossil fuels and is not biodegradable.

Source: bitsfrombytes