That depends on what your objectives for the UK/EU are. Why are you establishing here? What are you trying to achieve? Are you looking at taking on any members of staff?
If you are looking to test the market and understand what the landscape could look like, it might be better to register as a branch.
If on the other hand you already have customers/clients and are looking to gain more – it might be more beneficial to set up a Ltd company.
This page contains detailed guidance on the types of UK legal structures available.