Mining pools are groups of cooperating miners who agree to share block rewards in proportion to their contributed mining hash power.
While mining pools are desirable to the average miner as they smooth out rewards and make them more predictable, they unfortunately concentrate power to the mining pool’s owner.
Miners can, however, choose to redirect their hashing power to a different mining pool at anytime.

Pool Concentration in China

Before we get into the best mining pools to join, it’s important to note that most mining pools are in China. Many only have Chinese websites and support. Mining centralization in China is one of Bitcoin’s biggest issues at the moment.
There are about 20 major mining pools. Broken down by the percent of hash power controlled by a pool, and the location of that pool’s company, we estimate that Chinese pools control ~81% of the network hash rate:
China - 81%
Czech Republic - 10%
Iceland - 2%
Japan - 2%
Georgia - 2%
Russia - 1%

The Biggest Mining Pools

The list below details the biggest Bitcoin mining pools. This is based on info from Blockchain’s pool share chart:
We strongly recommend new miners to join Slush Pool despite it not being one of the biggest pools. It was the first Bitcoin mining pool and remains one of the most reliable and trusted pools, especially for beginners.

1. BTC.com 

BTC.com is a public mining pool that can be joined and mines 15% of all block. We strongly recommend joining Slush Pool instead.

2. Antpool 

Antpool is a mining pool based in China and owned by BitMain. Antpool mines about 11% of all blocks.

3. Slush 

Slush was the first mining pool and currently mines about 11% of all blocks.
Slush is probably one of the best and most popular mining pools despite not being one of the largest.

4. F2pool 

F2Pool is based in China. It has mined about 10% of all blocks over the past six months.

5. ViaBTC 

ViaBTC is a somewhat new mining pool that has been around for about one year. It’s targeted towards Chinese miners and mines about 9% of all blocks.

6. BTC.top 

BTC.top is a private pool and cannot be joined. It mines about 7% of all blocks.

7. DPOOL 

DPOOL is a Chinese pool and mines about 4% of all blocks.

8. Bitclub.Network 

Bitclub Network is a large mining pool but appears to be somewhat shady. We recommend staying away from this pool.

9. Bitfury 

Bitfury is a private pool that cannot be joined. Bitfury currently mines about 3.5% of all blocks.

10. 58COIN 

58COIN is a Chinese Bitcoin mining pool.