I bought my 4 new as I waited for a 5. Hind sight, the 4 was a lot of fun to drive, but seemed a little slow for 472 hp. It was amazing in and on curves. It would be an awesome track car and a fun DD as you don't have to worry about triple digit speeds in mere seconds.
That said, the 5 is such an amazing car. Fast as poop, it's truly bonkers, handles extreme well. It has never scared me with lack of traction or too much power. Agreed, it looks better. More features, more room. But....here's way I have one. It's the last and best of the V cars IMHO, not counting future EV's. Who knows if or when we go electric what will be there, but I don't care. It's a supercharged V8 with 668 hp. It is amazingly stealthy. I love mine so much as an overall package, I thought about buying another one or a "regular" CT5 V as a daily, even going back to a 4 as a daily. No one knows the future, but I think 4's will continue to drop in value, but the 5's will stay in the $90 plus range unless it's high miles, wrecked, or worn out, if that matters to you. You can have mine after you pry it out of my dead, cold hands....or is that my guns?