The best deck really depends on what cards you have and where you are in the game.
So basically you have to make the best of the cards you have in order that you can fend off attacks and have enough ammunition to actually defeat opponent's towers.
Here is a pretty good deck example which does not rely on many special cards:
Goblin Hut
Barbarian Hut
- These will provide a good steady stream of army, don't place the barbarian hut as your first card, it is too expensive - and easily countered.
Prince
Hog Rider
- These will enable you to strike quickly at the enemy, the Prince is great, but is easily distracted by your opponent placing a unit in front of a tower. The Hog Rider is super fast and will get to the tower more directly (unless another building is standing in it's way). If you don't have a Hog Rider, you could try a Giant.
Baby Dragon
Minion Hoarde
- These two units provide great air attack, the minion hoarde is super strong against tanks and other land based opponents.
Barbarians
Spear Goblins
- These two units will provide the strength in numbers that you will need to overwhelm your opponent.
This is just one deck example, there are many other strong deck options. For example if you have the skeleton group you may want to use that instead of the Spear Goblins because they will overwhelm The Prince, Giant and Hog Rider quite easily.
The Witch is also a great option, perhaps to be used instead of the Barbarian Hut.
I'm not overly keen on defensive units such as Bomb Towers, Canons, Tesla Canons etc... Just because I find them boring to use, but I come across many strong players that successfully utilise these units in their decks - Even if there bore the game to death when they use them!
Good luck in your deck building, and I'd be interested in know what decks the readers of this article are using and are finding success with.