Hi Gareth,
There are a huge number of excellent makers on these forums and there is no one answer to your question. As you look at the armour threads on this forum you will so the different opinions and advantages of many different makers then you make up your own mind on which best suits you. Different makers use different materials (ABS, FiberG, Aluminium etc) and each has different costs, wait times for the build, weight and finish qualities.
My advice is read as much as you can and then decide your budget and preferences.
I am doing my first BF ESB build myself and have been reading the threads over a year now, each time deciding on what parts i need and can afford and getting bit by bit.
Take your time and choose what fits your needs best.