it came down to OWC vs Kingston vs Crucial all which were around 270 bucks.While I'm sure there is some difference, it's by no means any common knowledge, and it honestly doesn't matter either way. There are other factors that are more important such as the RAM timings, frequency, etc. Generally speaking though, especially for an MBP, you're not going to notice any difference in performance. If the speed of the modules are comparable, I'd just go with the cheaper set as long as it's from a reputable brand.
So another question, do these ram modules come in 1Gb form? or are they all 512 or 256?There are no differences in performance.
Each 'black box' is a ram module. For a 4GB stick, you will see 8 of them. 512MB each module. For the 2GB stick, you may see either depending on whether they are using 512mb or 256mb modules.
Just make sure you get CAS latency 7 or below for MBPs. Also, make sure you have a well known brand and lifetime warranty.