I would go for slamless no.1. These players had achieved a greater level of consistency than the one slam wonders which I think is worth more because it requires a lot more effort. Sure, winning a slam is a great achievement but it's only one tournament and after that the level of tennis one slam wonders displayed was usually a lot lower. So, basically they had an amazing two weeks but then returned back to their old level. On the other hand slamless no.1s sustained a high level of play during a long time and did not win a slam due to mental pressure that was put on them by the haters and media and mostly,themselves. Nevertheless, they made a bigger impact and have a bigger name in tennis world.