Depending on where you look, or who you talk to, you'll get a varity of responses about the various brands of ballistic goggles on the market. Simply put, there's no such thing as a 'fits everyone wonder goggle'.
My personal favourites are Wiley-X SG1 and Gentex EPS-21. Both fit nicely under military helmets, but the Wiley-X's are the better of the two for civillian helmets. The Gentex goggles were specifically designed for Gentex PASGT and CVC helmets. Whilst the Wiley-X series have the benefit of being able to be configured as sunglasses, I find that they were designed as sunglasses for someone with a fat head (I need the sunglasses toggle strap to keep them on with the arms attached). Also in 'sunglasses mode', the lenses tend to rattle in the frames. These problems disapear when converted to goggles. Having said that, a few of my friends actually find the sunglasses option more comfortable under their helmets. Another avantage the Wiley-X goggles have, is that perscription lenses can be ordered from the manufacturer. So you dont have to clip 'flat' lenses into a special bracket inside the goggles (as you have to with most other ballistic goggle), you just replace the standard lenses. One main criticism I have for the Wiley-X goggles is, on initial inspection, they appear to be cheap and flimsy. The 'made in Taiwan' tags don't do much to alleviate initial concerns. However looks are decieving. One of my former bosses owes his eyesight to the Wiley-X SG1's he was wearing when a car bomb exploded beside the military vehicle he was travelling in. Wiley-X SG1's tend to have an average retail price of around $120AUD, so between $70-$100AUD is still a good price. Between $120-$160AUD is reasonable for SG1's with Light Adjusting Lenses (be aware that SG1-LA only come with 1 set of lenses). Anything more, then I wish that seller all the best of luck ;)
The Gentex EPS-21 have a higher ballistic rating to the Wiley-X goggles. Definatly what I'd be wearing if ever I was driving around some of the less friendlier streets of the world's troublespots. Day/night transitioning is a little easier with the Gentex goggles, since all you need to do is clip on/off a tinted lense that sits over the clear one (similiar to ESS and Wiley-X CQ). As I stated earlier, this goggle was designed for Gentex military kevlar helmets. I find it a little uncomfortable, as it digs into the bridge of my nose and the tops of my cheekbones. The main draw back is for people who wear presciption glasses. If you're one of these, then your options are contact lenses or get the special 'Rx' bracket and 'flat lenses'. Being Military/Law Enforcement issue, Gentex EPS-21's don't turn up on eBay that often. I've found a few online retailers quoting between $115-$155 for the basic goggle (goggles, lightweight nylon pouch and dark lense and/or amber lense). The closest you're more likely to find are ESS NVG Profile and Wiley-X CQ or Nerve Goggles.
Both the Wiley-X SG1 and Gentex EPS-21 are ventilated, though the Gentex goggles have dust filters. The Wiley-X goggles acheive ventilation through the shape of the injection moulded foam backing on the lenses. Both goggles feature 'fog' free lenses, but, like all goggles, they will fog up when you're stationary (or moving slower than 40kph :\ ). Anti-fogging is achieved by circulating air. You can use anti-fogging wipes to reduce fogging when stationary. And, again like most goggles, sweat will pool in the bottoms of the lenses (creating a nice 'underwater' effect in that part of your field of view). Unfortunately I've yet to discover a method, other than remove goggles from head, empty and wipe dry. This is enough for some to proclaim them (Wiley-X's in particular) as 'utter garbage/worst goggles ever'. Oddly enough, I was issued with a pair of Oakley A-Frame dust/dirt goggles many years ago (the ones with the black 'carbon fibre looking plastic front and foam around the back of the frames) and had exactly the same problems with them as I have with the Wiley-X's and the Gentex goggles. But, as I said at the start of this guide, there's no such thing as 'wonder goggles'. You have to assess what your requirements are for the goggles, and accept that there will be compromises.
Just a quick note about genuine Wiley-X SG-1 goggles.Depending on where they came from and what lens combo they have genuine Wiley-X goggles will either come in a microfibre cloth bag with a plastic clip (like Oakey and other sunglasses, the bag doubles as a cleaning cloth) or a hard plastic case. They may or may not have a Wiley-X box (cardboard red with dark red dots on the sides, Wiley-X eyewear logo inside a black oval on the front and back, plain black flaps and barcode sticker on the top and black with WX logo, phone number and website address on the bottom).
The ones without the box are usually new millitary surplus/overuns. They should have Wiley-X logo badges (the logos are a seperate peice to the arm) and Wiley-X SG1 Pat.USD 467262 printed in white, on the arms. They should only be available in Smoke/Clear. The coloured versions should come packaged in a box. If they are being sold as new then the clear lenses (complete with small, rectangular, black sticker that reads 'INTERCHANGABLE (printed in white) ANTI FOG LENS (printed in red) 100% UV PROTECTION (printed in white)' on the left lens) , the head strap and the sunglasses strap should all be in seperate, small, zip lock bags (with clear lenses bags stapled to each other) inside a plastic sleeve with the coloured lenses already in the frames. Depending on when they were packed, you might also find a microfibre cleaning cloth included with the microfibre bag (the cloth comes standard with the hard case). Head and sunglasses strap, bag and cloth should all have the Wiley-X logo screenprinted on them.
If your Wiley-X's came with everything and were in a box, then they are retail stock and should also include a glossy instruction sheet about the size of a Myer shoppping docket, with illustrated instructions for removal of the lenses on one side, and removal/replacement of the temples (arms) on the other. The box will also have a bar code sticker on the top flap that will have the model and lens combo printed on it above the barcode (eg. Wiley-X SG1 (in bold) Blue Lunar/Clear underneath in smaller, normal font). Apart from the lens colours, there's no difference between the retail and the military goggles.