When it comes to best desktop ad sizes there is no way around it. You want your website to look pretty but at the same time you wish you could earn more revenue. For desktop the best ad sizes can often be surprising in dimensions and just by adding a few pixels you could be earning a lot more.
There are many different solutions for increasing revenue out there and this can get confusing very quickly. Usually if you are using an already established partner that for example uses header bidding solution they will already have some data on what would be the best desktop ad sizes for your specific website. For example Adsense has some pre defined dimensions that you can use, but how to know which are the best. If positioned well the wide banner sizes can earn you significantly more..