Enlarging lenses are like camera lenses - the difference between the cheap ones and quality ones can be staggering. I am always amazed that a lot of people who have really expensive cameras and lenses print with cheap crapolas and wonder why they can't get 'quality' in their work. They are quite willing to spend enormous amounts on taking the picture but resent paying anything to print them.
The most important difference you will find with a good enlarger lens is 'punch'. This is actually to do with lens flare and contrast. Expensive lenses control this better so you get a better dynamic range on your prints - and you start getting detail in the highlights and the shadows (these are usually muddied out by flare).
Schneider do a range of lenses - KSMatt explained the difference between comparon, componon etc 'cause I get them mixed up (I just look at the price! ;-) ) somewhere in another thread. Personally I use Nikon lenses - but Minolta do a good lens as well.
Unfortunately enlarging lenses are like so much else in Photography - personal preference rules and the overall set-up makes a difference too. I used some pro colour facilities to do some prints once and they used Minoltas. I couldn't believe the quality. When I could afford it I bought a Minolta lens but on my enlarger it didn't match up to my Nikons. I learned that the enlarger and light source make a difference to the lens. My enlarger is a big old Durst. The ones at the lab were Besselers.
That aside - any high quality lens will knock spots off a cheap one.
