They are both old by now and you have to check very well how much rust, how good and long service history is etc. I think the bmw era rr had best seats in terms of comfort and leather longevity. 400k+ km and they still look nice if they have been looked after and it is same with rest of the car.
Yes, many newer jlr rr had cooled seats and that’s very nice extra on summer days.
Bmw era rr are cheaper to run and later 4.4 jag engine is not so common since 3.6 was by far more popular choice.

Personally I hated the BMW seats. My ass would fall asleep legs would numb. The plastic trim on the seat breaks. The plastics in the interior are horrendous and the paint peels, the faux leather on the door peels and bubbles.

The later model had a much better quality interior with real leather, better plastics and finishes imo 2004 L322 V8

Different bums, different results.

On our 2009 Subaru, I get out and hobble after even a few km drive to the shops but I'vbe driven over 1,000km in a day in the 2003 L322 without a sore bum or back.

I can't comment on the M62 BMW engine reliability as I've only just racked up 250,000km in mine without any major issues - except oil leaks. It's probably due for timing chain guide replacement. Ron B. VK2OTC
2003 L322 V8 Auto
2007 Yamaha XJR1300
Previous: 1983, 1986 RRC; 1995, 1996 P38A; 1995 Disco1; 1984 V8 County 110; Series IIA