Question, are custom wetsuits as warm as the branded ones?
Titanium lining / micro fiber etc
If this question was popped a year ago, I would lean towards the fancy fabrics, such as fleece, titanium/silver-lined and whatnot. They do have their benefits IMO, but wetsuits tend to warrant a replacement pretty quickly, making it a huge sum of money to part with each time they lose their insulating properties.
Fleece, does have a very obvious benefit though. It keeps you nice and toasty both on the surface and underwater. Layering fleece based wet wear such as Fourth Element Thermocline, Sharkskin or Lavacore under a regular neoprene wetsuit makes a lot more economical sense than having one built into a wetsuit, as they don't need replacement as much as neoprene does.
As such, my experience with neoprene suits is that having a good fit and seal is more important than the material. Using the money saved to get good under layers or a good hood is much more worth it.
A little tongue-in-cheek - here's a little of what some of the internet think of fancy materials as well - http://www.scubaboard.com/community/threads/titanium-wetsuits-good-science-or-good-marketing.332100/