Haltech Platinum 1000/2000 are very good ECUs, but as with all things it comes down to money and how far away a good mapper is who has experience with your ECU of choice.
If you have an up to £2000 budget my moneys on the Syvecs S6, it's the little brother of the S8 which is basically a rebranded Cosworth Pectel SQ6/Life Racing F88. Both of which are awesome ECUs.
To put this into perspective the Sierra Sierra World Time Attach EVO runs a Pectel SQ6 and Life Racing PDU (both of which are UK hardware interestingly).
There's also plenty of AEM units kicking around. AEM have just released a new ECU that's meant to be up there with the big boys: -
AEM Infinity 10 Standalone
This should be in at around the £2k mark, not sure if it's actualy released in Europe yet, but the spec looks good and quite different from previous offerings.
So plenty of options.
In all fairness it depends on what you want from an ECU, the more expensive ECUs can control lots of other hardware (anti-lag, water injection, nitrous, traction control, DBW etc) and intergrate with the CAN bus system for full electronic control over the car, most daily drives won't need anything like this and as such a more simple ECU is probably all that's required.
I guess the best option for a daily drive is limit yourself to around a £1k budget (excluding sensors) and you will have a powerfull ECU good for any normal upgrade you want.
If your building a high HP Time Attack car then the skys the limit, I've scarily budgeted £8k for electronics (ECU, DPU, Custom harness and install/mapping)