Enviro-Solutions Graffiti Remover
Most effective for: painted and unpainted smooth surfaces
Least effective for: concrete
Largely a good product. It does not run while wiping as it has a viscous consistency. It is ideal for the majority of smooth and hard surfaces as well as graffiti types. The amount of time the product is supposed to be left on the surface depends on the surface and graffiti type. For instance, leaving it for 3-5 minutes may work better in certain cases whereas, in others, the product can respond immediately to the graffiti. Moreover, it can disturb the paint of the surface in certain cases, however, that is more likely to happen due to scrubbing. However, the product does not completely get rid of graffiti on concrete surfaces and only fades it out.
SOYsolv 1
Most effective for: painted and unpainted smooth surfaces
Least effective for: wood, painted concrete
The product has a trigger spray bottle and is overall effective. However, its smell is really strong. It works efficiently on both painted and unpainted smooth planes without rubbing off the paint of the surface as much depending on the graffiti type. It also works to some extent on plastered concrete, in that it removes the majority of the graffiti paint however it leaves some shadow. On wood, it smears the graffiti a bit but does not get rid of it completely. It may perform better on wood and concrete if a pressure washer rinse is done afterward. The product may be more effective in some cases if left to sit on the affected area for 3-5 minutes.
BG-Clean
Most effective for: painted and unpainted smooth surfaces
This product has a trigger-spray too. It works particularly well when trying to remove marker graffiti from smooth surfaces. Its performance may vary for other graffiti types. Generally, the product does not cause any disturbance to the paint of the surface unless a scrub pad is used aggressively. It works pretty similar to soapy water.
Taginator
Most effective for: wood, concrete and unpainted brick
Least effective for: metal, painted concrete
With a trigger-spray for application, the product works exceptionally well on surfaces like concrete and unpainted brick, especially if the brick wall is relatively new, smooth and less porous. However, it has a very strong smell. You may need to scrub the spray paint off using a stiff brush and water, rinse if the brick wall is more porous. You can avoid some of the brushing if you have a power washer. It may not be the best choice for painted surfaces as it can remove the surface paint.
Lift Off #3
Most effective for: unpainted plastic, unpainted and painted metal
Least effective for: painted concrete
The product can be applied using a trigger-spray. While it performs fairly well on surfaces like unpainted plastic and metal, it is important to be careful while using this product on painted surfaces as it may easily remove the paint from the surface. It does not work as well on painted concrete and only dulls the graffiti instead of removing it. The product also claims it can remove graffiti done on fabric.
All of these products are excellent for the purpose of graffiti removal.