if you want to compare, look at their 1) throughput, 2) seek time, and 3) access time.
If you're concerned with speed... get 2 7200 RPM drives and hook them up in raid 1. Or get 4 and hook them up in Raid 10 (for a bigger drive). IMO, spending money for fast platter drives is a waste, and spending money on SSDs is a waste right now, because prices will come down soon. the cheap ones are too small to make use of, and the big ones are too expensive to justify for the non-wealthy consumer. if money is no object, get some gorgeous big SSD's and watch them fly.
With ssd, it all depends on what it connects to. If it is designed to "enulate" sata by connecting to a sata port then it's not much quicker than a sata as it is restricted to sata data transfer speed. If ssd is connected to it's own dedicated interface in a pci-e slot then it has the potential to be a lot faster.
At the moment, because of cost, it's just not worth it in my opinion.
We have some Toshiba R500's in the workshop at the moment. They have ssd in them as standard and I can't say they are any quicker than sata as they have the ssd connected via the sata interface.