To answer the original question - what makes those who flew her so fond of her?
It may sound like a cop-out, but the answer is - if you didn't have the priveledge to fly her, you will never know.
She was unbelievably manoeuverable - pull up over a ridge, rack on 140 degrees of bank and pull down the other side then slam her wings level - she loved it. On a SAROP, winching at 50ft - if the winch-op asked for a 6" movement, you could do it - she was so stable in the hover with all the weight (engines and Cbox) in the nose. SH into a rough field - no problem - just zero speed her (with those balloon tyres and massive oleos) in to any site you like - no problem.
Why was she so amazing. Simple. Whilst she may not have been the best in the world at any one thing (and I bet she she was), she was really good at EVERYTHING.
The RAF have not been able to replace her for one simple reason - she can't be replaced. Our modern helo's are bland, specialised and compared to the Wessex - limited. They all do one thing perfectly - she did everything well. I know which I think is better.