Aberystwyth is in the North of Wales and is nearby to the university of Bangor, these universities are not in large cities. They are quite small and next to the west coast and so the weather can seem very rain centric. My brother went to Bangor and really enjoyed being so close to the mountain range and the hiking, there are less places for drinking if that’s your thing. They have great horse riding places and loads of outdoor activities you can enjoy.
Newcastle is known for being a party town, it’s a much larger university in a much larger city. I personally am really looking forward to going there. It’s also a Russell group university and the name will be well known on job applications as being more prestigious, (I’m not sure how much these things matter on job applications nowadays but I’m told that they can mean a lot). The North of the UK is also extremely friendly (I grew up not too far from Newcastle) from what I can tell. But of course much busier than Aberystwyth and I can understand why people won’t want to go to unis in large cities.