@prismara
If you can find an 060 card without having to sell a kidney, grab it with both hands.
There is a wealth of demo material that runs fine on 68030, but I am afraid you heard only the truth regarding more recent demos. I have a 68040/25MHz and a lot of the most recent ones absolutely crawl on it. I have one of those Blizzard PPC/680x0 cards you heard about, I bought the 040 version when I got one as I felt I really needed all my internal organs ;-) I was also pretty sure that the PPC would provide a better upgrade path for future software and that the 68040 would be fine for most cases, which it has been.
However, a 68030 can often be a life saver compatability wise if you wish to run older software.