15 extra BHP, lots of options as standard such as Sports exhaust, Sports Chrono, PASM, GTS Alcantara Interior & Exterior, Porsche Dynamic Light system, Sports Seats Plus, smoked rear lights......
You can spec an S with most of that but the cost would be slightly more than a GTS and you'd not be able to have the exclusive GTS interior and exterior stuff nor the extra 15bhp.......
No brainer if you're buying new imo