It is just personal preference. With the 1.75" I should have about 1" of rake which I prefer. The 2"+ gives the appearance to me that the front is higher than the rear. I know this is not the case and just "looks" this way, but for me I prefer the front to appear a tiny bit lower. Plus when I have weight on it, unless its heavy I am not nose high. If your familiar with PD Diesel on YouTube, his truck is identical to mine and he is running 1.75" coils with extensions and loves the setup. He seems knowledgeable and I love how his truck turned out. My last truck (21 3500) I ran 1/2" Thuren Coils and had around 1.5" or so rake, so this time around I figured I would go 1.75" and lessen it a bit.
Stock my truck right now sits exactly two inches higher in the rear (1/2 tank fuel) so If I went 2" or more I think I would get that front end higher appearance and I definitely do not want to lift the rear to remedy that.