From what I hear, they can all be very variable.

With Evri, where my brother lives their regular driver is on the ball and they get so much stuff from Next they've become friends. My SiL no longer books returns, just builds up a pile and texts him (I have no idea what advantage that has though). He's also in the local Facebook group and troubleshoots any problems, so things go pretty smoothly. I don't think I've ever met my Evri driver but it's always the same guy and deliveries go smoothly. However, I know approximately where my depot is and it's rough there - they've been ramraided a few times or just had some scrote wander up to a driver with a hammer and politely request their keys.

The problem with Evri is that it's all franchised out so the local depots and drivers are all self-employed and largely providing their own stuff, with everything pared to the bone. So the potential for something to go wrong is higher. If you have a good regular driver then things will run smoothly, if you just have cover drivers dropping in who don't know the area then it can very easily go pear-shaped.

"Evri" is the new name for Hermes, isn't it? From where I live, I now refuse to order anything that uses them. At best incompetent, at worst thieves and criminals. Not had a problem with any other couriers, or the normal post. It's interesting (and surprising) to hear that it's not the case elsewhere.