Tom's Hardware maintains a Hierarchy list that gets updated once a month:

http://www.tomshardware.com/reviews/ssd-review-benchmark,3139-6.html

So if you were going for 120GB then in order of best to worst (although worst is relative here, compared to a HDD anyway ):

1. Intel SSD 510 120GB (Tier 5 )
2. Crucial M4 128GB (Tier 5 )
3. OCZ Vertex 3 120GB (Tier 6 )
4. Patriot Pyro 120GB (Tier 8 )

If you see a OCZ Vertex 3 MAX IOPS EDITION 120GB that is a Tier 3 drive!!