Looks like head has finally overruled heart. There is nothing you could do to an X1/9 that would ever achieve the performance of either of those 3, which all come with the ABS breaking required for anything doing sub 8 secs, I should know, a car pulled out of a side road in front of me in the Boxster and 'pop-pop-pop' as the ABS rapidly brakes-release-brakes, I stopped on a dime. The X1/9 at the same speed would have been through the other side.
Then there's the handling, air-con, performance, and comfort of knowing you'll be driving well within the limits of the car, and modern technology and build quality will see a well maintained car last many 10,000 of miles.
The only problem is that these cars are too good and too fast, in that you don't really get that engine note until you're doing warp speed, and the handling is so slick you sort of miss that go-cart, raw feed back, but you're talking 0-60 in 11.5 seconds for an X1/9. I love my X1/9 for what it is, and ripping around on short excursions is heaps of fun, but for any long trips, where I want to know I'll get there in the end, and can have the air-con on the entire time without having to nervously watch the temperature gauge, it's the Boxster.
For me it'd be down to two, the Boxster as the better handling and historical relevance, being mid-engined and the model accredited with saving Porsche, or the BMW Z4, being faster and harking back to old classics of big engine up front, rear wheel drive. The SLK is a bit Beverly Hills housewife for me (ironic when the X1/9 was labeled a hairdressers car in its time, cute and pretty and not overly macho).
Yeah, the Brits haven't made an affordable open top for decades, closest would be Lotus, and Alfa have had their GTV/Spider variants, then the Brera & Spider variant, but the 4C is a bit pricey, but no more so than the Lotus. Fiats Arbarth unfortunately is still a Miata with Fiat badging and a tweaked engine.
