I use both name brand & generic (including A-Data) microSD/HC cards on a wide variety of devices with very little performance variance. Only when you get into higher end dSLR cameras and Hi Definition video capture devices will the rated card speeds make much of a difference. The processor/RAM bottleneck is significant enough on the LG Rumour that it won't really matter. What's more important is that your device actually *supports* the large size cards, such as a 16GB. Many do not, and it's sometimes trial and error.
For better prices I highly suggest supermediastore.com. I've been using them for about five years give or take with no problems whatsoever. Here's a link to their selection of 16GB microSDHC cards. You can pick up a Ridata card for $45.99 shipped (including adapters).
Meritline.com is another site I use, but a little less frequently. They tend to be a bit higher and focus on the name brands.
I've finally upgraded my phone from an original LG Rumor that I've had a couple years now to the new Samsung Instinct s30 (wish I could of gotten the Instinct HD but either way I still love the Instinct phones and will be keeping this one till it works no more) that I will be receiving tomorrow but the 2GiB MicroSD card I bought for my LG Rumor when I first got it will be no where near enough for all my music, well actually it already is too small to hold even half my music, and I'm assuming the Instinct can play videos so I will have some movies on there too but they will be converted to a lower resolution so they will be only a couple hundred MiB's. So I went to NewEgg.com looking at all the 16GiB MicroSDHC cards and narrowed it down to these:
RiDATA ($48.99) - http://www.newegg.com/Product/Product.aspx?Item=N82E16820183245
A-DATA ($62.99) - http://www.newegg.com/Product/Product.aspx?Item=N82E16820211378
OCZ ($67.99) - http://www.newegg.com/Product/Product.aspx?Item=N82E16820227489
Each are 16GiB, MicroSDHC, Class 6, memory cards leaving the only differences being brand and price so I figured since so many flash DRIVE tests can be found on Google I'll look for MicroSDHC reviews/tests on Google but the results aren't the best and I didn't really find anything at all to help. I know I'm being picky here but could anyone tell me if they've had any experiences (good/bad) with these cards, if theirs one even better that you recommend (has to be 16GiB and Class 6), etc. It's going to be a couple weeks before I can save up the money for one of these memory cards so I figure I might as well take the time to make sure I get the best.