I have a Sherwood Magnum regulator. I am the third owner, Dad...Sister...Me. I'm sure it wasn't serviced annually. Probably stuck in a box in the basement. I took it in before I started using it, and nothing wrong, just normal preventative maintenance.
It has been a very good regulator for me. I like the wide exhaust tree. From what I hear it's practically bullet proof. It isn't balanced so when my tank drops below about 1000 psi, I can usually feel that some extra work needed to get the same air. This really isn't a big deal.
That being said, I will probably replace it in time, but it's one of the last things on my list. For an inexpensive, no nonsense, low maintenance regulator, it's hard to beat. I got mine given to me. If I were buying a regulator, I would have to seriously look at other options in the smae basic price range (Zeagle DS V or Envoy Deluxe) .
A buddy just bought an Oceanic GT3. It is balanced and has an adjustable flow rate dial. Both nice options, especially the balanced first stage. Last weekend he seemed to be having an issue with it not giving him as much air as it used to. I asked him if he needed to adjust the knob, which he did. I'm not sure if it helped any.
His reg 8 months old, has 15 dives on it, my Sherwood probably 8 years old, who knows how many dives, still works as expected.
It's a difficult decision I know. If at all possible, try to use the ones you are considering before you buy. Hopefully your LDS will have demo models available. You may want to try a high end regulator for comparison so you know what a really good regulator should feel like.