Agree with onehunga.
There are lots of people who have family or work ties in the UK and can't go to the US for extended periods. There are other people who just don't want to. That's why there are so many options - because there are so many of us, and we're all different.
Assuming none of that applies to you, and you're free to go to the US, have you factored in the cost of flights to and from the US? Accommodation when you're out there? Car hire? Bear in mind that you will need to come back to the UK to do you IR test, as there are no examiners out there.
Where do you imagine your first job will be? I'd guess it won't be flying to, or in, the US. Far more likely to be instructing in the UK, or flying short-haul flights to/from regional airports in the UK and possibly Europe. There are differences in the way the airspace is constructed and used, and some small differences in the use of the r/t - nothing major, but possibly enough that, given the theoretical case of two identical job candidates, but one of them trained in the UK and one in the US, it might make a difference.
Even if it doesn't make a significant difference to your job prospects, you have to assume that you won't find a job immediately, and that you'll need to do some flying between finishing your course and finding a job, just to stay current. In which case, any instructor at any school you're going to hire from will most likely want to spend some time bringing you up to speed with the UK system.
Nothing against doing it all in the US, so long as you go in with your eyes open. Know exactly how much it's going to cost you (not just the flying, but everything), and budget for any extra time you'll have to spend getting to know the local procedures afterwards.
Personally, I would suggest a compromise. Do your PPL in the UK. Do some hour-building abroad (maybe South Africa or Canada - not the US, though), then come back to the UK and do some more hour-building here and in Europe. Do the CPL in the US (this is why I said not to do the hour-building in the US - if you're going to go to the US for the CPL you may as well get as much variety as possible and go somewhere else to hour-build!) Then do the IR in the UK. But, as onehunga says, that's my personal preference so it doesn't necessarilly apply to you.
Good luck!
FFF
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