I prefer the old Trek with the original SFX. But I can't really separate that from my interest in old SFX.
I actually don't mind these "improved" versions being created. I just think they should ALWAYS be packaged together with an un-edited original version. (No exceptions or excuses. No bullcrap like the Star Wars lasersdisc cuts on the DVDs. The original version must be equally high-quality, equally easy to view, etc.)