What to choose: an endpoint antivirus, an EDR solution or both?

EDR (or XDR) is the new coinage for endpoint security technology. 

Although those good old days antivirus software were doing the same thing, signature-based detection and response against that defection. But the modern threat vector has changed a lot and everything is quite complicated these days. So, the protection mechanism also. 

Almost all leading cyber security software vendors have come up with newer versions of endpoint protection, sometimes with AI as well. 

So, if there is an option, it is always better to go with EDR of anything "*DR". But keep in mind that cyber security has to be implemented in every layer of ISO. 

The “Antivirus” protection technology is replaced by EDR which does include a modern version of “antivirus” along with other ways of device protection. 

Multiple vendors provide EDR: Trend Micro, Cisco, etc.

The more current technology is XDR.

Next-Generation Antivirus (NGAV) uses a combination of artificial intelligence, behavioral detection, machine learning algorithms, and exploit mitigation, so known and unknown threats can be anticipated and immediately prevented.

Endpoint detection and response (EDR) is a solution that combines data collection, data analysis, forensics, and threat hunting, with the end goal of finding and blocking any potential security breaches in due time.

For the current attack landscape, you need both NGAV + EDR in a single product for better protection & remediation.

but the current trend is

XDR (Extended Detection and Response) collects and automatically correlates data across multiple security layers – email, endpoint, server, cloud workload, and network. This allows faster detection of threats and improved investigation and response times through security analysis.

Antivirus lifeline (as a separate tool) is limited now. 

All the products are now combining EPP and EDR into a single solution. I would rather prefer to go with XDR solutions which will help to detect and as well as remove the existing one from the system.

If you look at a product like SentinelOne, it is both EPP and EDR (and much more...). In that case you only need this single product.

You could take a look at this short explanaition on YouTube: EDR? EPP? Both?!? See how to explain SentinelOne in just 2 minutes