3.0 would help if connecting it directly to the computer, and having a 3.0 compliant slot.
The thing I should point out here is that the USB 3.0 compliance will have no effect on media card readers unless they're designed to take advantage of that on the native connection to the motherboard (unless you're using an external, in which case it'll still need to be compliant on the reader, and use a 3.0 usb slot.)
The xfer speed to computer really would not hurt much, as most media cards still aren't even reaching the read/write speeds of standard USB 2.0 so I don't see it making any difference to be honest, and a 3.0 compliant device will still work just fine in 2.0 slot, it'll just slow it down a little, but as stated the card can't even read at usb 2.0 speed anyways, so yeh.
Also, the transcend has no reviews on Newegg, indicating it's new, or people just don't trust it, and since that's the case you have no benchmarks to go off of to make sure that it's actually NEAR 10 speeds.
The thing to note here is that classes on SD cards are for the Maximum read/write speeds. there's no guarantee you'll get what's advertised.
So I say just go with the gskill, it's cheap, has good reviews, and will do what you need on the phone.
