Cactus V5 is probably the best of the "eBay triggers", if you're looking for a low price point. About $60 for a pair. The Phottix Stratto IIs and the Yongnuo RF-602s have separate Rx/Tx units. The V5s and Yongnuo RF-603s are transceiver units. All four operate on 2.4GHz, so have similar range/interference issues).
The 602s are probably the cheapest (around $30/pair), but use non-standard sync ports (Olympus 3-pin connector, so you end up buying proprietary cords from Yongnuo) and the Tx unit uses a non-standard CR2 battery. All the other units use AAAs, iirc. They do have a PC (in) on the transmitter, though, which is fun if you have a camera without a hotshoe that has a sync port, or you want to use a dumb optical slave with a point'n'shoot's pop-up.
The Stratto IIs (about $90/pair) use a 3.5m jack for sync, and have a TTL pass-through hotshoe (which theoretically might work for Oly if you get the Canon version), and allow for group selection, but only four channels.
The RF-603s are less expensive (also around $30/pair) and have a pass-through hotshoe (not sure if it's TTL or not), but do not have locking rings on the feet, channel selection (of 16 channels) is done with dipswitches in the battery compartment, sync ports are PC (in) and 2.5mm (out), not 3.5mm, and the test button only works if the unit is mounted on the camera hotshoe (using a meter becomes something of PITA). Oh. And the RF603s and RF602s have the on/off switch placed exactly where you can't reach it once a speedlight is mounted.
The Cactus Vs have locking rings, channel selection (of 16) is with a dial on the side, it uses 3.5mm minijack sync, and the on/off switch is where you can easily reach it. AND there are m4/3 shutter release cables for both Olympus and Panasonics, which the Yongnuo's (and afaik, the Strattos) don't.
For better reliability, or inter-operability with other pieces of gear, the Paul Buff Cybersyncs
are probably a better bet if you're using Alien Bees/White Lightnings/Einsteins in concert. The PocketWizard Plus III
s are going to be the most reliable and will work in concert with their TTL units for Canikon, as well as the Multimax, Plus and Plus IIs. But in both of these cases the cost is going to be higher.