When I was looking for a car, I test drove EVERYTHING. 2014 Mercedes c300 (too small for me), 2014 Acura TL (Bucket seats made my love handles noticeable lol), 2015 Q50 (Loved the car, very pricy, wasn't blown away), 2014 G37S and 2014 G37 (sport bucket seats were the same as the TL, G37 seat all the way back was still too short), the 2014 MKS (interior was amazing, very upscale compared to the SHO, but I hate the front grille. Its a grandpa mobile), the 2014 MKZ (The biggest problem I had with the 2.0T is the Lancer / Passat Dual clutch delay. The dual clutch is supposed to help shifting, however, it creates a noticeable delay between shifts. The engine just didn't feel engaged with the road at any point in time) and the SHO.
I chose the 2014 SHO because of the engine, tune-ability, and the other features. The suede seats are very comfy, it has every single feature you do and don't want (rain sensing wipers, heated and cooled front seats, auto high beams, heated rear seats, good sound system, 20" flower wheels, digital interfaces, etc. Not even the q50 had the same feature set and that is Infinity's new flagship G series vehicle. I even went to the point to take the q70 out, but that was too high up in price for what I wanted out of a vehicle, especially since the Taurus SHO was faster, had more features, AND it was almost 20k cheaper.
My opinion is stick with the SHO, or go the Bimmer route with the 335xi. Both vehicles I did a lot of work and tuning with. Both vehicles are stupid quick. The MKS is great but grandpa like (no offense MKS guys), and the MKZ is the little brother who just isn't quite ready for the race.