What lens is the best for Canon 5D?

any lens can shoot any subject. If the main purpose of buying a camera is to take portraits, I'll give you some advice:

If you want to take care of scenery, travel, souvenir and environmental portraits, I suggest buying a standard zoom lens. The cheapest one is 5D 18-55IS, which is practical, cheap and imaging is ok. A slightly better choice is Tenglong A16, and the price of parallel imports is in the early 2K. Good imaging, constant large aperture, suitable as a hanging head. A better choice is Canon's professional lens 17-4L, which has good imaging and good color. One of Canon's cheapest professional lenses, licensed in the early 5K and used in the early 4K. The best choice is Canon's 16-35L II. Excellent imaging, constant large aperture, but the price is too expensive, licensed in the early 1W.

if it is a portrait or an artistic portrait, you can consider a large aperture fixed-focus lens. The cheapest choice is Canon's EF 5/1.8 spittoon, which is cheap, has good imaging, poor workmanship and loves to run out of focus. A slightly better choice is 5/1.4 from Sigma or 5/1.4 and 85/1.8 from Canon. Sima's imaging is good, but it is out of focus. Canon's 85/1.8 imaging is very good, but the focal length is a bit long, which makes it more troublesome to shoot the whole body. The best choice is Canon's 35L 5L 85L 135L, except that the price of 135L is around 7K, everything else is tens of thousands. The alternative choice is that Leica and Zeiss will transfer for 5 days. The imaging is perfect, but the manual lens is more troublesome to use.

There are many other optional lenses, such as EF 28/1.8 35/2 for environmental portraits and Xiaobai and Guo Xuwei for artistic portraits.

if you buy licensed SLR products, you will get a one-year warranty, while parallel products will generally have a one-year store warranty. It's the same after more than one year. Joint guarantee needs an invoice, but it can be done without it. If it is broken, you can just get an invoice. There is definitely no refurbished machine, but there is a unpacking machine. If you buy licensed goods, you can buy the intact machine. If it is an intact machine, you don't need to test it, just buy it directly.