If you're a Nikon/Canon shooter on a budget I highly suggest the Yongnuo RF-603 flash triggers. Because I shoot sony, I am stuck using Cactus v5's which do exactly the same thing but are larger and cost more. These are the most affordable options for sony's new hotshoe and since sony has enough going for their cameras at the moment that I'm happy to overlook this. The Yongnuo RF-603's are about $30 for a pair and come with a shutter release cable for your camera so that it can double as a wireless remote (ensure you get proper version for your camera model). Amazing value. The Cactus V5's run about $75 for a pair.
Although I've seen no difference in reliability, the Cactus V5's differ from the Yongnuo RF-603's in a few ways.
-To their credit, Cactus was able to fit a 1/4"-20 thread on the bottom
-Switching channels is easy w/ dial on exterior (whereas the RF 603's channel switches are under the batteries).
-They work with the Sony Multi Interface Hotshoe (Sony A7r, A6000 etc). Since I need this I overlook all the negatives to the product.
-First of all they are notably larger (and don't really offer more features)
-They are more than 2x the price
-In real world use I've found the channel dial on the outside to be frustrating as it accidentally gets switched
-Trigger must be in transmitter or receiver mode whereas Yonguos can just stay in Transceiver (Trx)
-Larger 3.5mm trigger port that is less universal