I think the worst Ferrari you could buy would be a cheap one. If you want one, dig deeper in your pockets and buy one that is cherished and properly sorted.
I've always liked the 308, in particular the early ones. When you look at how mental 246 Dino prices have gone, they do seem to be relatively good value. Years ago one of my regulars bought a 348GTS unseen (he got a Ferrari specialist to go and look at it for him). Unfortunately, he's 6'7" tall, and found he could only sit in it with the roof panel off. Still, he managed to sell it for what he paid for it, and at least he can say that he's owned a Ferrari.