The reality is, it depends what you want to do. ACP can be a great role and is highly respected (within most areas-medicine being the area where I've seen them be treated as glorified F1's). However in ED, I have only seen them be respected, but it is worth noting that training and support will differ significantly depending on where you do your training.
The reality is, whilst ACPs have been integrated really well within some clinical areas, in others it has proved more challenging. Usually (in my experience) ACP's work incredibly well within ED and the role has been well brought in. They have national accreditation through RCEM and therefore there exists a national standard for them. This is not true for ACP's working in other specialities.
I would say the very good ones end up working at Senior Reg level, but their pay does not necessarily reflect this.
However, to become an ACP you need to be an experienced practitioner prior to applying for the programme. If your interest is EM, then you would probably want to look at either RN or Paramedic. Paramedics though have limitations on their practice and if they do become ACP's, they can not currently complete the prescribing module- although I suspect this might change.
It is also extremely competitive and those who apply will regularly have 10+ years of experience with a multitude of PG quals.
For me, I've been an RN for 9 years, but choosing the medical route because; you are not tied to 1 speciality straight away, internationally recognised qualification, it is a defined role, opportunities in pre-hospital (or better), increased scope of practice. etc....
The choice I suppose is do you want the role of a Doctor or the role of an ACP? Whilst they can overlap, they are different.
Do you have the grades for Medicine, if you don't ACP would be a great path to go down and you would end up working at a similar level.
Hope that's helpful