It depends what you are looking for. Coast or inland? Urbanisation with other expats or a more Spanish environment?
Areas north of Alicante tend to have better public transport. You may have a car now but that may not always be the case.
As you are retiring, I would recommend you find somewhere with easy public transport access to a doctor and a hospital. This last week my husband has been in San Juan hospital. We no longer have a car and I have had to spend one and half hours each way travelling to visit him every day. In this heat that is very exhausting.
After only visiting both, we decided on north because it felt like somewhere to live - not holiday permantly - if that makes sense! However, only time will tell when we have lived there for a while. But I agree - spend time in both as we are all wanting different things from life.
Thank you folks for your thoughts. I didn't know about the better transport in the North. Have holidayed in Moraira area for 25 years (on and off) and aim at retiring in the area ('cos we know it and like it) but didn't want to dismiss Torrevieja area out of hand. As it's only a couple of hours away maybe, when we rent this winter (4 mths) we'll drive down a couple of times; may even stay over!