If you're basing your decision on cosmetics, user reviews, or other opinions, you'll be missing a lot of important factors.
The are resources on the web that do
empirical testing, and make
recommendations based on far more than the "it works" standard.
Others perform
teardowns to reveal what is inside, which can betray the standards (or lack thereof), to which these products are designed and built. Apple's adapters aren't perfect, but just looking at the photos and comparing to other brands indicate why they often cost more.
The physical form factor of the UK plug (whatever qualities its proponents advocate) isn't conducive to the qualities most valued today in a wall adapter -- compact and powerful, so the selection will be more limited, and some of the more regarded products may not be available to you.
But, there are some good, even inexpensive choices are available, such as IKEA's SJÖSS models (
45W 2C,
30W 1C).
One is 10 quid, the other six quid. Well-regarded, economical, and backed by a good return policy if not to your liking.
The 17 Pro Max peaks at a bit over ~40W maximum power consumption, so the 45W model should be a good fit in 1C mode, and the 30W for a bit more leisurely, but still rapid charge rate. There's also a new 65W model, but it doesn't appear to be available there, at least yet.
Regardless, at the minimum, I would look for legitimate safety marks, which will eliminate many of the inexpensive, gibberish- or no-name adapters pushed on Amazon and other marketplaces like Aliexpress. You have to ask yourself whether saving a few quid is worth the risk of burning your house down. That applies to all electronics. If it seems too good to be true, it likely is.
Even the big, reputable brand names aren't immune from product faults, but at least they'll make a genuine effort to recall the units and compensate owners. That's not going to be the case with an Amazon seller who is pushing electronics this month, but may pivot to clothing or other goods next month, or next year, if they don't vanish altogether.
