The best I have found for travelling is the 3-pin (it has the earth pin) SKROSS - Pro Series adapters
https://www.skross.com/en/products/world-travel-adapters
Why?
1. I travel a reasonable amount, it has never let me down
3. As it’s a plug adapter, as well as a multi-USB socket device, it serves two purposes
2. It is well made
3. Its USB three sockets are more than adequate for most purposes
4. The device separates into two parts. That means that if I am only going on a quick trip into Europe and am likely to only need one USB connection, I can take just the single USB part
5. The pins retract into the body, which means I do not have ridiculous British pins sticking out all the time
6. The earth pin means that it’s suitable for running higher current draw devices, for example my girlfriend’s hairdryer with its bloody British 3-pin plug
I have married this to:
A. Several of the strong Anker USB leads, including two of their 3 meter leads. Why so long? Easy.... it is Sod’s Law that the plug socket will be nowhere near where you need it
B. A simple small continental 2-pin but 3-way socket splitter, that I bought in France years ago. Why? Easy.... again, it’s Sod’s Law that the only convenient single socket will be the one for the bedside light and you can’t otherwise have both the light and the travel adapter plugged in at the same time
C. A charging brick, such as recommended by er-minio above. The new ones are USB C compatible and / or offer ‘fast charge’
D. One Anker car cigarette lighter dual-USB adapter
With that small collection I have safely charged, laptops, phones, cameras, Bluetooth headsets, Apple watches, portable speakers and all manner of other USB compatible devices, at home, in hotel rooms, in a taxi, in airports, in cafes and restaurants, on the move on my motorcycle and.... and..... and....
PS I believe that international jet jockey Arsey’s employer gives their pilots the SKROSS adapters free. He recommends them, too.