When it comes to enlarging lenses, you get what you pay for. The Rodenstock Rodagon, Schneider Componon-s, El Nikkors or a Fujinon EX are all good lenses. These are all six-element double gauss designs. The Apo Componon or Apo Rodagon have a slight edge over their siblings but you may have trouble with variable contrast paper per certain authors. I have confirmed this for myself but you will have to experiment with your particular system. The best ever enlarging lenses are the EL Apo Nikkors. They were made in 105, 170, 210, and 300mm focal lengths, are diffraction limited wide open and are down right spectacular. The 105 covers 35mm wide open and 6*7 at f8. They were rare even when Nikon made them but now that Nikon no longer makes them, they are akin to unicorns. Should you be so lucky to find one be prepared to pay a pretty penny. The last time I saw one for sale at B & H (~1987) they wanted over $3000 for it.(posted 8835 days ago)My philosophy/advice is buy the best lens you can afford since every printed picture flows through the enlarging lens.
I am not sure that there is a "best" enlarger. The more features/conveniences, the more you pay, so it is a matter of comfort. Make your self comfortable.
And don't forget things like enlarger alignment, carriers etc that can make a great deal of difference.