I've not used one but I like my clocks to be the sort that pick up a radio signal from the atomic clock at the National Physical Laboratory. As it's got an accuracy of no more than a 1 second error in a 138 million year period, there's a pretty good chance of it showing the right time ;-)
With that in mind, and looking for the best customer reviews on Amazon (as well as a decent price and mains power, so that you don't constantly need to change the batteries), this is what I'd go for:
https://www.amazon.co.uk/gp/product/B01145GMQ0