I was really dead set on buying a conical for a few months... I was just obsessed. But I didn't want to spring for it so I was leaning towards the plastic as well.
However, I finally came to the feeling that the plastic conicals are just not worth it. All over these forums, you'll see advice telling you to not use plastic buckets for fermenters too many times because they scratch so easily and can harbor bacteria. I feel like the plastic conicals are just as prone to scratching. As we say with a lot of things around here "it works perfectly fine... until it doesn't." And then you have a very expensive bacteria farm.
Another reason I decided against one was getting my priorities straight. I really wanted a conical, but I was not even controlling my fermentation temps at the time. Temp control is a verified way to make an improvement in the quality of your beer, whereas a conical really just makes life a little easier. Do you have plans for how to control your temps if you get the conical? To me, it seems the easiest way is to buy a fridge solely for that purpose. There are probably some more economical methods that require some extra effort.
So if you've got solutions for both of these, then I say go for it. But plenty of people brew great beer without them, harvest yeast just fine, and save hundreds of dollars. Personally I'd rather spend on all sorts of cool brewing equipment like refractometers, etc.
