With respect to the 997 at the time I can see this but as the 911 has evolved past 997 it's gotten
worse in my opinion. The two cars are merging too much. The 997 looked very much like a rear-engine car while the 987 looked very much mid-engined. These later 911s have slid those cylinders so much closer to the axle line and in fact the RSR was literally mid-engined. Meanwhile the 981 and onwards have attempted to look more 911-like. Overall I think the 987 is still the most svelt and pretty Cayman, even though I dislike its front graphics in particular.
Of those four, the 987 is much more of its own unique shape.
My problem with the 991+ is the too-short front end. Compared to the "classic" 911 shape it feels very stubby. I think they did this to shorten the wheelbase, but I've never gotten used to how it looks from the side. I genuinely think that the 996.1 with the factory aero kit is the best looking of the water-cooled Porsches. As a general rule, for me, in terms of design: 911 > Boxster > Cayman > 911 Convertible. I'm gonna take a stab at ranking them, excluding the 911 convertibles:
1. 996.1 911 (
highly dependent on spec but I just find them so pretty and perfectly proportioned)
2. 987.2 Boxster (best looking Boxster of the lot, particularly in Spyder form, fixes the un-athletic proportions of the 986 without getting into fussy or flabby like the 981)
3. 997.1 911 (arguably the cleanest design of the water cooled 911s, but I find them a little plain compared to the 996.1)
4. 987.1 Boxster
5. 991.2 911 (remarkably better looking than the 991.1, an outlier in this list)
6. 997.2 911 (IMO unnecessarily fussy compared to the .1,
ridiculously overpriced compared to the .1 cars...)
7. 992 911 (These things look
tough, especially in black. I'm not sure how that jaw line on the front will age though. The 992.2 is so similar that I'm covering both of them here)
8. 982 Boxster (way tidier than the 981, comprehensive upgrade design-wise. Genuinely might be my next car...earlier 2.0/6M cars can be had for as little as $30k)
9. 986 Boxster (I still think tragically underappreciated - I still find them better looking than any of the Caymans. As with the 996, very dependent on spec. They had 16" wheels on some of these cars...)
10. 987.1 Cayman (Best looking Cayman, but they still have some really weird angles. Probably the most athletic looking car in this whole list though, some real FD RX-7 tautness)
11. 987.2 Cayman
12. 982 Cayman
13. 996.2 911 (I just don't like the changes to the front end)
14. 981 Boxster (worst Boxster - I hate the rear end design of these cars particularly those dorky tail lights...which sucks because they are probably the best value P-car out there at the moment)
15. 981 Cayman (worst Cayman, these cars just look flabby to me and the rear end is not any better than the Boxster version)
16. 991.1 911 (the most meh 911 in history, if it's not a GT3 or Turbo they just blur into the background for me. Some really tragic wheel designs on these 911s too).
I think Porsche design was at a low point around when the 991/981 were being developed, which they have definitely recovered from. Obviously the list above is just based on looks, the Caymans are still great and offer the best dynamics of all.
I've got my eyes on a 982 Boxster 2.0 as my next car. By my calculations (based on
this scheme I developed) and assuming a mild 91 octane tune @300tq [stock is 290], even the 2L will deliver a 1.27∑tq/weight figure, which blows away a 3.2 987 Boxster S which is only 1.08∑tq/weight, which means at peak torque, the 982 2.0 should
feel around about fast as a C5 Z06 Corvette, but still have all the wonderful driving dynamics of a MR Porsche.