Big 4 Corporate Finance (Regional Office) vs Mid-Tier Corporate Finance (London)

For those who don't know corporate finance at an accounting firm is basically working on middle market transactions doing the same type of things you would do in an M&A group at an investment bank.

I have an offer from a Big 4 firm in a regional office. Don't want to give too much more away as it would be personally identifying but this regional office is on one of the islands surrounding the UK that acts as a tax haven (think Guernsey).

I have another offer from a mid tier accounting firm (BDO, GT, etc) for the same role in London.

My preference is to do what is best for my career. At first glance it seems taking the Big 4 role makes more sense but then there are a few things that are diverting me towards the other offer.

1. Living and working in London
2. The isolation of working in a regional office.
3. The fact I will eventually want to transfer to London within 2 years anyway
4. Friends, family and girlfriend who all live in London