If your laptop is on the potato side I would personally avoid kde, it’s much lighter now than it used to be but still heavier than other options. Mint looks good in my personal opinion and, again in my opinion, is a better alternative if compared to ubuntu, it’s based on it but with some improvements. The default flavor comes with cinnamon, but if your laptop struggles it’s also available with xfce, which even older machines should be able to handle.