I particularly like Microsoft Lumia 950 XL to get the benefit of bigger screen for media consumption, games and better windows experience on the phone, better battery life, cutting edge hardware and liquid cooling tech which sounds awesome to me.
Anyway, both are great smartphone to date. I like the build quality, best 20MP rear camera, improved selfie camera. 3GB of RAM means the phone works like a champ. I used to own Lumia 720 (RAM 512BM) and Lumia 925 (RAM 1GB) but they worked perfectly fine for me. I love the smoothness of windows phone.