It wasn't an easy choice for me to make for sure, it was years in the making starting from when I first tried Ubuntu way back.
Ever since that time, when I swung back and forth between Windows and Linux I saw Linux slowly getting better and better. The last few times I tried Linux I installed Ubuntu again, Lubuntu, Xubuntu, Kubuntu, Ubuntu Mate but each of them had their own quirks that didn't work right for my laptop. Performance was very good on the Dual Core (apart from Ubuntu) but there were either problems with the menus, strange bugs with standby and none of them really felt right.
Mint Cinnamon is the first distro I came across so far that feels right, it has a menu that doesn't have buggy behaviour, laptop standby is working great, terminal output is fully scrollable, and best of all the integration with WINE seems to work better in LM than it did on the other distros.
I went ahead and even installed it on my desktop too!
Also, another reason for me is that LM is its own distro, it isn't just another flavour of Ubuntu which means that it has fixes, its own desktop environment, its own identity and also the benefit of the fixes already applied to Debian and Ubuntu itself baked into it by the 3 separate development teams. So it's like being stable 3 times over, if the way I'm thinking of it makes sense lol.
I can't wait to see what version 21 will be like.