Over the past five years, CPU performance has hit new and unforeseen heights, and processors are increasingly spending time waiting on data from hard drives. This is what makes storage today's most glaring bottleneck. Overcoming it requires an SSD.
At the end of the day, the real-world differences between SSDs in a desktop environment aren't altogether very large. The most important jump happens when you go from a hard drive to (almost) any solid-state drive. With that said, there are measurable attributes that separate one SSD from another. But you'll need to approach a purchasing decision as the sum of many parts. Within individual apps, you'll hardly notice the difference between most SATA 3Gb/s and faster SATA 6Gb/s drives. It's the more taxing workloads that make a faster device worth owning.
Sequential performance is an important SSD attribute, but there are points beyond which it's difficult to make use of the performance in a real and meaningful way. That's why the hierarchy chart below relies on information provided by our Storage Bench v1.0, as it ranks performance in a way that reflects average daily use for a consumer workload. It's simply a ranking using one metric, and not gospel. But as far as single-number performance is concerned, it is serviceable for our needs.