The four big specs are random read/write and sequential read/write. All of the mfgrs like to blather on about their incredibly fast sequential speeds, but the only time that matters is when you are doing a big-assed file copy or disk backup. More important are the random read/write speeds. The bottom line is most of the current generation
SSDs have similar enough performance in real world conditions where you don't really have to focus on these four specs.
The thing to focus on is: how reliable is the product? You can wander Newegg ratings and look at the 1 and 2 star ratings and get a feel for which SSDs are crap. Lately, I've been pushing Crucial's m4 and the Samsung 830 as they seems to have decent reliability and because they aren't using a Sandforce controller (my personal bias).
Two additional things to look for:
- Does your OS support TRIM (eg: Win7)? If not, be sure to get an SSD with a manually triggerable garbage collection utility or one that just doesn't degrade much w/o TRIM.
- Are you on a Mac? Then only buy SSDs that are known to work on a Mac.
Also a +1 for getting at least 128GB. Smaller SSDs have less memory chips and read/write channels. so, performance can be noticably slower. If you want numbers, take a look at Anandtech's SSD Bench