Based on my many years with a W123 I’d go with the Mercedes.
The Mercedes AMG GTR is about 600 lbs heavier and 110 HP less than the Ferrari and 160 HP less than the McLaren. It is also less expensive so there is that advantage. When I was out of college in 1985 I invested aggressively and have continued since then. In 2013 I bought an Audi S6 and a Mercedes C300-4-matic, both for cash. My next car, whether McLaren 720S at the top end or Mercedes AMG GTR at the low end will be for cash too. I have not had any debt for a very long time.