Which Is Better Out of the Canon EF and RF 50mm f/1.8 Lenses

With many Canon photographers making the transition from the EF DSLR mount to the RF mirrorless mount, there are questions over whether it's worth adapting your current glass, or selling it and replacing it with the RF versions where possible. So, how do they compare?

Changing mounts is one of the most expensive transitions a photographer can make, and requires a lot of careful consideration and planning not to go down a large financial rabbit hole. I've only moved once, and I spent months spreading the change out to make sure I got the best deals for everything I bought and everything I sold. However, it worked out cheaper in some situations just to buy an adaptor for my old glass and use it on the new mount. There can be negative effects of this — there always some downsides — but it's often worth it when it comes to weighing the cost up against the benefits.

In this video, Alex Barrera compares the Canon EF 50mm f/1.8 STM with the new Canon RF 50mm f/1.8 STM using the Canon R5. The first thing to note is that these two lenses are about as cheap as brand new lenses can be, at less $200 even for the new RF mount 50mm. So, this isn't really that useful for helping you decide whether you should keep the EF version to save money, and more an interesting look into how different the adapter EF lenses are from the new RF versions in terms of results. I'll let the video speak for itself, but I must say, it's close. The RF does appear a little more on the nose wide open, but the differences are so slight that if you were going to buy an adaptor (or you already have one) then I wouldn't bother replacing the EF version. 

What are your thoughts? If you have Canon mirrorless bodies, are you going to adapt your old glass, replace the lenses with the RF versions, or a blend of the two?