Well....
I'm not objective either so I've avoided responding up to now.
I've been diving in dry suits since before Bare was called Bare. My first drysuit was a prototype trilaminate suit, custom made for me in 1989 from a company called Fitzgerald (which is now called Bare) and all of my drysuits since then have been Bares..... that's not an accident, and tilts my hand.
With all due respect to ajduplessis I can actually give you some facts about dry suits.
Regardless of manufacturer, Neoprene suits thinner than 7mm are made from "crushed" neoprene. There are three types of Neoprene suits. (1) Untempered (whatever you want to call that), suits made from 7mm neoprene, (2) suits that are made by putting the neoprene under high-pressure to reduce the size of the bubbles in it during processing (generally 5mm in thickness) and (3) suits that are neoprene but thinnner, which are crushed neoprene that has had a layer shaved off.
The main difference in this category falls out into two main characteristics.
the first is buoyancy. The thicker the suit, the more buoyancy it has (and therefore the more weight you need to compensate). The reason for the shaved neoprene is to reduce the amount of weight needed to keep it under water.
The 7mm suits are.... frankly... awful, and it doesn't matter who made it. a 7mm neoprene drysuit has a LOT of inherent insulation but the buoyancy shifts betwen the surface and say... 30m are significant, which make them pretty much useless to recreational divers. They're cheap to buy, but that's for a reason... They're crap.
the 5mm suits (regardless of who makes them) are good for recreational divers... point out. They strike a good balance between warmth, buoyancy characteristics, robustness and price that makes them popular and good choice. Moreover (and this is both a strong point and a weak point) 5mm suits are virtually indestructable. They're popular among serious wreck divers because you could swim through a hail of knives (which is what serious wreck diving sometimes feels like) and the thick, robust neoprene offers tank-like protection from pointy things that will make holes in most other suits.
The 3mm suits ( the shaved ones ) are a good choice for divers who want a neoprene suit and are willing to pay a bit more for more flexibility and the abililty to dive deeper. From what my friends tell me, the 5mm suits lose too much buoyancy on dives deeper than 50-55 metres to be useful for deep diving beyond recreational limits. That's bad if this is what you're doing but the 5mm suits are fine for the other 99% of the world. If you have aspirations of diving deeper on the short term then you should choose a trilaminate suit (read down). Like the 5mm suits, the 3mm ones offer much more robust protection from a hail of knives than the average trilaminate suit
.......
Ok... now the other major alternative... bilaminate and trilaminate.
Both of these can be seen as plastic coated tent material... They have no affect at ALL on your buoyancy and have no inherent insulation. They are the preferred suits for divers making regular dives deeper than about 30-40m because of their buoyancy characyteristics but you need to think a lot more about the undersuit... with a neoprene suit, the undersuit, looks more like something you would ski in... with a trilam suit, it often looks more like a sleeping bag. The point being that the undersuits are more bulky and therefore need more ballast. A trilam suit may act more balanced at depth, but that doesn't necessarily mean you'll need much more weight to dive in one....
The BIlaminate (bi=two layer) and TRIlaminate (tri=3 layer) differ in difficulty in manufacturing (and therefore price) but also differ in how robust they are.
The most well known BIlaminate suit is the Bare Nexgen. it's inexpensive, a bit loose fitting and very prone to developing leaks. You can fix those leaks with a bicycle repair kit but believe me, having an unexpected pinhole leak that sprays water in your crotch during a 90min dive is enough of a pain in the ass that I wouldn't recommend them.
Trilaminate suits are made by most manufacturers including Bare. Sometimes they have an external cover of a tough fabric and that makes them much more robust. Some manufacturers, like DUI and UR, charge (a LOT) of extra money for this robust external layer and some, like Bare, do not. That's a major difference.
Nevertheless, this post should give you a good idea of the different technologies and what they can do for you.
There is one last point to be made.... the valves. There are two main manufactuers of inflator and deflator valves... Si-tech and Apeks.
In my personal opinion, Si-tech valves are better. They're smaller, they work better and they don't leak. The apeks valves, on the other hand, are larger, they don't work as well and they leak.
That's a bit of a generalization but I think a lot of drysuit users would agree with me.
Bare uses Si-tech valves, as do many others, an example of a suit that uses inferior valves is the DUI (despite it's high price).
.......
Ok... now why you read this thread.... what should you buy.
I can't really advise you but I can say a few things that I think you will find valuable
- do not buy a 7mm neoprene suit
- do not buy a 5mm neoprene suit if you intend to dive deeper than 50m
- if you intend to dive in a hail of knives (ie. wrecks) and at recreational depths then I would tend to prefer a 5mm or 3mm neoprene suit to a trilam suit
- if you want to spend your money on staying dry then don't buy a bilaminate suit (for rentals they're excellent, but not if you own one)
- if you want to dive to extreme depths or you are looking for a good all-round suit that can grow with your interests, then I would tend to choose for the trilam suits provided it has a sturdy external layer.
- buy a suit with si-tech valves if you want to stay dry because the alternative is serious crap.
R..
