Lenses depend on what type of image you take, How you view them, how much you can afford to spend,what weight limit you have. etc, etc, etc,
An L series 600mm IS USM is a fine lens. But if you buy one to put on you RZ 67 so you can take macr images on top of a mountain ..........
One of my all time favorites was a minolta Rokor 24mm that I almost had welded to the front of my old X-700. But I found it difficult to take detailed pictures of Sun Spots....
Probably the most versitile, and best value for money,lens would be a high quality standard(50mm equiv in 35mm specs or 80mm in MF), which when added to a good pair of legs to move closer or further away, would undoubtedly produce the finest results.