I have printed with the base lenses that come with enlargers, besseler and rondenstock omegron 3.5, and those 4 element lenses are useable but just junk. 4 Element lenses seem to only work well with longer focal lengths. I currently use a Rodagon 50mm 2.8 and a Componon S 50mm 2.8 and those two lenses are just beautiful and sharp. I also use a nasty el nikkor 50mm 2.8 that has deep cleaning marks and fog over half the front element, but it works and is useable at f8.

I can only recommend any 50mm lens thats f2.8 with a 6 element design. No need to get an APO unless your doing color work. The brighter lenses will help with focusing, and exposure times as you only need to stop down to f5.6. Some also have nifty light up indicies to show your aperture.

Honestly with the prices of enlarger lenses the difference between a f3.5 lens and a f2.8 lens is very small. The only problem is getting a nice version, try looking for a closed shop thats selling of its stuff, as there were significant differences between lens to lens from the same manufacturer and make. Smarter printers (like from commercial shops) bought a few and tested them and returned the rest, only accepting the best copies, if they read some of the testing literature on enlarging lenses.