First time owner

You can get a ton of information by perusing the model-specific forums on this site. I would start there.

Obviously you get a lot more performance with a 355, and you get far fewer things to break in a 328 GTS. For example, the 355 Spider has a complex electric-mechanical top mechanism that can be troublesome; the 348 has a manual drop top; the 328 has the removable hard top. The 355 is still a big jump in price over the 328/348.

It may be an oversimplication, but I think you tend to get more performance at the price of more expensive service and parts as the cars got more computerized. The 355 is sometimes considered the most expensive V8 Ferrari to maintain. The 328 is usually seen as the least expensive (assuming it's been cared for... any neglected Ferrari is bad news).

If you've always liked the 348/355, maybe poke around those forums and sort out what you like. The spider came later in the 348 life cycle ('93 I think), by which time Ferrari had sorted out most of the problems with the earlier cars.

Regarding insurance, there are several threads about this -- do a quick search using 'insurance' and you'll find some good discussions. My experience has been that my 328, insured as a second car, is reasonably affordable just because Ferrari owners tend to be extremely careful, and usually more mature, drivers.