These are best Bitcoin mining farms offering cloud mining contracts.
 
I've picked Cloud mining services which:
a) have proof of having huge mining farm, backed up by Bitmaintech or other ASIC manufacturer
b) have atleast 40% ROI (considering all fees) when contract become obsolete.
c) have known owner (company)

 

1. HashFlare 5*+

This is my most favourite company. For a simple reason. It turns out highest profit. I'm with them for 2 years without i single glitch. Everything works extremly well.

HashFlare is a new range of cloudmining services brought to you by the HashCoins team of cryptomining experts.

Our team has been involved with cryptocurrencies since the inception of Bitcoin and has over 3 years of experience in the field of mining cryptocurrencies.

Our goal is to make mining accessible to all users regardless of age, location, investment, technical nouse or experience. We want to give our customers an opportunity to try out cryptocurrency mining and earn Bitcoin as a reward. On a larger scale, we hope to contribute to the development of mining services and subsequently to the development, establishment and adoption of Bitcoin both as a currency and as an economic system.


Available languages: English, Russian, German, Italian, Spanish, Portuguese, Greek, Chinese, Japanese.
Features: Pool allocation (manual hashrate distribution between bitcoin mining pools).

* – If maintenance payments exceed the amount of rewards for mining the equipment will be switched off automatically

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2. Gigahash 5*+

Giga Hash Ltd. offers Bitcoin Cloud Services an easy and safe way to purchase hashpower without having to deal with the complex hardware and software setup.

The company is registered in Bulgaria / European Union and operate under EU and Bulgarian law.

We start mining on December 2013 and continue to grow in 2014. Тhe idea to create a company and launch our own business came after several private investors wanted to invest money in crypto currency like Bitcoin. Our first investor was a sailor who wanted at all costs to invest in Bitcoin, but knew nothing about mining hardware.

The services we offer are geared to such clients. Understand the importance and future of crypto currencies, but lack the necessary knowledge and free time to dig alone.

 

 

3. Genesis mining 5*

Genesis Mining is the largest scrypt cloud mining provider that offers several features that are unique among all cloud mining services.

Our integrated advanced multipool is the most popular feature among our clients. This means that an algorithm will automatically mine the most profitable altcoins. The trading engine converts the mined coins to Bitcoin (or Darkcoin) and users will receive their payouts directly to their Bitcoin/Darkcoin wallet!

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This very efficient way to mine Bitcoin is what we call “Smart Bitcoin Mining”.

Why you should mine with Genesis Mining:

Your mining experience is just a few clicks away. Mine Bitcoin the smart way!