Tinsparrow,
Rather difficult to answer your questions as they are too general. For the quality of training, it is the training provider, not the continent that makes the difference.
For flying in the UK, my personal feeling is that your biggest enemy is the weather which is vastly different from the US (or at least Florida where most of the cheaper training venues are). UK training can be very stop start at certain times of the season, but returning from a PPL completed in the US leaves you ill equiped for our environment (far more controlled airspace and rapidly changing weather conditions). ONce you add airfares and accomodation, the price gap narrows although you would still save by going abroad. If you are intent on going abroad, don't just look at the US.
One of the biggest advantages of the UK is that you can visit a number of training providers to see their setup and exactly what you get for your money.
With regards to employment, obtaining a PPL puts you on course for the modular route, but in all honesty I don't think any airline is worried about where you trained for a PPL as to them it is a "hobby" licence. There are many theories as to whether airlines care where you did your CPL and IR training, but I would suggest go where you find the training best suits your purposes. This is not always the cheapest as it is money wasted if you can't pass the CPL or IR flight tests.
Regards
Obs cop