Both the original 135mm lens on my ancient DeJUR 4x5 enlarger and a somewhat later f/5.6 135mm El-Nikkor cover 4x5 negatives well enough. However, if you have high enough darkroom ceilings and long arms, a 150mm might be a better choice. The main advantage of a maximum aperture of f/4.5 is easier focusing without a focusing aid. Any modern high quality f/4.5 or f/5.6 lens should provide fine sharpness and contrast. Even my older lenses suffice for me.