I could name many Porsches other than 911 and explain their appeal to me but since that list is enormous I will try to explain the appeal of the 911 for me as it is probably the quintessential Porsche for many.
I like the fact it can trace its history and basic concept back to the 356 ( which in effect can be linked to the Beetle which was also designed by Porsche ) and they've persevered and continually developed what was basically a flawed concept from the start ( rear-engined sportscar ) and actually mostly succeeded and thereby creating a truly unique car compared to all other sportscars.
The fact that the Porsche 911 is basically a contradiction between a flawed concept and a company always aiming for perfection is what appeals to me and its developed character ( although overly familiar ) will probably never be replicated again as in today's world it would make no sense to start with this basic idea.
The shape combined with a rear-mounted air-cooled flat-6 ( which sounds great, especially without turbo's ) and its ability to be an everyday car for decades makes it the perfect antidote to Italian supercars ( which I also really love for being everything Porsche isn't ).
Basically you get it or you don't, as with a lot of things and a lot of cars.