PET carboys are light to use fermentation vessels as compared to glass carboys which are really heavy and require assistance while holding or changing space. The home brewers confirm that a full gallon glass carboy is potentially dangerous to use due to its weight. One small bump is all that is needed to turn the process disastrous.
Th thing is not only the beer process will fail but the shredded and broken glass will be all over the place. In extreme cases the holder reaches the emergency room for stitches. PET carboy is thus more durable, less dangerous and most importantly easy to carry and use. No breaking happens and if it does (like 1% chance) then no one is hurt in the way. Also the PET carboys are textured for a better grip.
PET carboys win hands down if one talks about the larger neck and opening, making it easier to clean the equipment once brewing finishes and it also gives better access for pulling out secondary additions. One can buy a PET carboy that can easily install a spigot. Or go ahead and buy an already built in one. When it comes to installing a spigot in a glass carboy it is definitely not recommended.
The cleaning process also becomes easy when you have a PET carboy as there are many cleanser available. A jet bottle washer can be used to spray away any yeast, hop, or protein trub accumulated in the bottom of the carboy. One can use Carboy cleaning tablets and simply fill the carboy with hot water and drop in the tablets. Carboy cleaning tablets, Alkaline brewery wash, elbow wash all the cleansing methods work for PET carboys and they are easier to clean as they weigh less when filled with water and are easier to drain.