Depends what you have in store for it bud. If you want to go down engine modifying rout then definately get a Jap as ecu is easier to chip. If want to keep standard and enjoy it for what it is and have the money get the UK, insurance will be cheaper and residuals would be better and resale easier than jap to sell.
All depends on finance, and what you have planned for it. Both Jap or UK are equally good options depending what you are planning
+ 1, Zedrush talks sense for once What you planning for the car mate and we should be able to help you more? What you hoping to spend?