Ofcom published its first comprehensive research into the performance of mobile broadband across the United Kingdom, but failed to take into consideration one extremely important factor: price.
While O2 emerged as the fastest mobile broadband provider in the UK (especially during the peak evening period) and the one offering the lowest latency of the five big mobile operators, the Telefonica-owned network has one of the weakest ranges on the market.
At the time of writing, O2 had only one USB modem (the Huawei E1752) and one tariff (1GB with Unlimited Wi-Fi for £10.32 on a one month rolling contract). If you want more data allowance? O2 doesn't offer that yet.
In comparison, 3 UK is the only mobile operator in the UK to offer unlimited data download (also known as 'all-you-can-eat') for as little as £25 per month on a one-month rolling contract. You need to use your mobile phone as a mobile hotspot though, a feature which is available on most recent handsets.
If you don't want to go that way, Three offers two dongles, the plain HSDPA one and the faster Premium dongle that is up to 40 per cent faster. A 15GB tariff will cost £15.99 per month on a two year contract while the faster Premium dongle adds another £2.04 to the monthly cost.
In a nutshell therefore, 3 Mobile is faster when using the Premium HSPA+ Dongle, cheaper for power users who don't really need Wi-Fi and way more flexible if you go through the tethering route.