I own a Diamond trilam - much like a DUI TLS 350 but with a heavier zipper and fabric. They are no longer in business, but the point is you can find DUI quality or better in a trilam for less than DUI price. A portion of the premium price for any DUI suit is, sadly, for the name. A trilam of any brand is fast drying, fairly durable fairly lightweight, easy to patch, and can adjust to a wide range of water temps. The trilam has historically been a very good choice for the "do everything" role. The downside is that the non stretch material requires a larger and baggier fit, particulalry in self donning models. In addition a suit that is large enough for freedom of movement with heavy underwear is really baggy in light weight underwear and in the reverse case a good fit with lightweight underwear means restricted mobility with heavy under garments.
I also own an O'Neil 5/7mm neoprene dry suit. The advantages of uncompressed neoprene suits are that they are stretchy and you can get a snugger and more streamlined fit in a suit that swims much like a wet suit with less air movement and less need for gas in the suit for either warmth or to eliminate squeeze. In my experience, a neoprene suit is hard to beat for warmth in really cold water (40 degrees or less) and their improved steamlining makes them faster in the water. The current neoprene suits are head and shoulders above the older Poseiden Unisuit as the cut and valve arrangement is such that they do not require significantly more weight than a trilam with heavy underwear. Cost wise they are 1/3 to 1/2 the price of a trilam. The downside is that you cannot make then run cooler so they do not offer the warm water options that a trilam does.
Compressed neoprene offers some flexibility and a bit snugger fit than a trilam, but like uncompressed neoprene suits they are heavy, slow drying and harder to repair. They offer some advantages of both neoprene and trilam suits but carry the disadvantages as well.
I recently bought a White's Fusion and I have to say that so far I am impressed. It is a different approach to drysuit design and construction. It uses a very baggy bladder layer contained inside either a spandex or 1mm neoprene and spandex skin (available with pockets) that creates compression and streamlining without restricting mobility. The advantage is a reasonably priced suit (around $1300) in a few stock sizes that will fit well in both lightweight and heavy underwear and swim almost as well as a wet suit in the water. Donning the suit is a bit easier than donning a snug fitting neoprene suit but is a bit harder than donning a loose trilam. The zipper however is great. It runs from the top of one shoulder in front under the inlet valve and up to the top of the other shoulder. This makes the neck seal and top portion of the suit more or less a lid you flip over and close after you are in the suit and allows easy self donning without an excessively long torso or restriction in mobility.
I am not yet sure how durable it is (although Fdog reports having well over 100 dives in his) but it promises to truly be the one suit that will do it all with no significant compromises and do it at a good price.
The boots on the Fusion are just a sock that goes into a rock boot style boot (think Converse canvas high top tennis shoe on steroids). This style of boot is available on other brands of suits, most noteably DUI, and is worth considering as it makes it easier to accommodate wide or high arched feet without the cramping issues you can get in normal dry suit boots without having to go to boots that are 2 or 3 sizes too large.
