There are many different game engines available to developers, some have unique features and offer a better workflow compared to others.
Firstly there is the UDK engine. This engine has won numerous awards for its ease of use and flexibility. It features many advancements that allow the artist to create realistic worlds and create what is needed for the project. one such feature is the Terrain modifier. This feature allows the creation of hills, mountains and other environmental features with relative ease. there is also Matinee animation and Kismet which allows for the scripting of events, animations etc.
Another very interesting engine is the Frostbite engine. This was developed by DICE in Sweden and is a very powerful engine. It features highly developed lighting which allows for incredible visuals and also incorporates the ability to render rich colours in game. This was one feature that DICE specifically wanted to create after they worked with UDK to create Mirrors Edge, and incorporating this into the Frostbite 2 engine, allowed them to create the richly coloured Battlefield 3. Perhaps however, the most significant feature with Frostbite 2, is the ability for buildings to be blown up and the cover of walls to be chipped away at with bullets.
One engine that i find particularly interesting is the CryEngine. It features a fully dynamic lighting system without the need for light mapping unlike the UDK engine. It also incorporates a dedicated facial animation editor, sub surface scattering and independent AI programming to allow NPCs to have sight, hearing and awareness of there surroundings.