Traditionally, fans of the tower defense genre are divided into two large groups.
Some people like games in which you can set the tower in large numbers, forming intricate maze of dozens defensive structures.
For fans of the heavy fire studio Red Machine has released an excellent game Goblin Defenders Steel and Wood. Read more about this project here: http://redmachinegames.com/en/games/goblindefenders.html
Other players like when the level design of map gives only a few slots for your towers. Careful selection of defensive tactics, the special role of towers improvements, thinking through ways of passing the level - these are features of this tower defense projects type.
Fans of these games will be pleased with our project Goblin Defenders 2: http://redmachinegames.com/en/games/goblindefenders2.html
Still not sure what game you are interested in more? Try both;)