You need to have public transport nearby, it's different if all your friends and family are in a rural area. You can be restricted by lack of choice for services, eg will you easily have a choice of carers if you need them, and simple things like getting to the docs, which sadly tends to happen more often as you age. If you are a way away from shops etc can you get the items of your choice delivered?
I am on the edge of a small town on a railway line with frequent trains - buses not so good. Traffic can be horrendous, so although I do drive sometimes I just can't face it. I have doctors, library, shops within easy reach also I can get easily to the countryside, and to be honest if I lived in one of the villages I'd be no better off from the point of view of countryside, and would have to start most trips to docs, shops, etc I'd end up coming back here anyway. A good friend does not drive and is very constrained as to getting out and about, bus from village tying up with the bus to town etc, and not much on a Sunday or bank holiday, it has really made me think. I've been asked would I go and live somewhere like Norfolk where lots of people go to retire, and without family there, really no, hospitals a long way away, bus services being cut, banks closing, etc
But basically one child lives nearby and the other about an hour and a half away. They don't want me too far away for when I am older and I don't want to be too far away from them. I'd happy relocate to where I'm from as I could find somewhere nice on bus routes, in the country but not too far from town, but I'd have to travel to see them, and I've decided that once mum goes I'll just visit the area instead. Locally I can get on a train to London and when I retire I hope to be able to go to exhibitions etc there regularly.