Ok, so i'm going to attempt to get past some snake oil I see in this thread.
The name on the package does NOT hint towards the quality of the RAM. The actual chip manufacturer does however. The major RAM manufacturers are actually samsung, toshiba, mushkin, micron and hynix (off the top of my head).
Just FYI, most of the 2011 macs have hynix chips in them (atleast the 3 i opened up did). On the other hand, Crucial and G.Skill are just purchasers and resellers of the above RAM names I mentioned.
So onto the confusing part... Companies that resell RAM, tend to switch their actually memory supplier based on the current market prices. This is why people recommend matching RAM based on batch number (so you know the memory came from the same supplier/batch to match consistency).
Anyway... I'm starting to babble. Long story short, 90% chance youre buying the same thing for a different price. If you have the ability to look at the RAM BEFORE you purchase it, i'd recommend mushkin chips... many like myself have had the best luck with them.
(People who don't believe me, take a look at your ram and see whos name is ACTUALLY on the memory chips and not on the packaging)
Examples:
Samsung memory with samsung chips -
http://img.photobucket.com/albums/v367/Iron_Eagle/NBR/P1020034.jpg
Micron memory with micron chips -
http://megamemory.com.au/82-150-thickbox/micron-2gb-ddr3-pc3-8500-1066mhz-laptop-memory-ram.jpg
Crucial memory with micron chips -
http://pan.fotovista.com/dev/0/3/09765230/u_09765230.jpg
Kingston with micron chips -
http://i01.i.aliimg.com/photo/v0/320493587/high_quality_sodimm_laptop_ddr3_ram_memory.jpg
Kingmax (never heard of this junk) with micron chips -
http://i01.i.aliimg.com/img/pb/418/060/268/1284974278103_hz-myalibaba-web-temp2_2720.jpg
hynix memory with hynix chips -
http://megamemory.com.au/88-158-thickbox/hynix-2gb-ddr3-pc3-8500-1066mhz-laptop-memory-ram.jpg
so on and so forth