Sorry for the late reply.
Anyways, COD 3 I just simply wasn't a fan of. I felt the writing was too cheesy and didn't do justice to the actual events, the characters all basically the very typical war stereotypes, and the actual gameplay and mission design wasn't very memorable either. It was basically just a watered down version of COD 2, without any of the memorable setpieces, and it was also a step down visually. Treyarch hadn't yet fully gotten a handle on things (heck, it was made in just eight months), and it shows.
As for Infinite Warfare? Well, there are many reasons why I actually am a big fan of it. Looking back at all the futuristic COD games that featured advanced movement, this is the one where they pretty much threw realism out the window and went full on Gundam/Macross. And honestly, I actually really preferred that approach compared to the attempts at staying grounded seen in AW and BO3. The campaign especially is one that I think ranks as one of the best in the series. From the extremely creative levels and mission design, through to all the optional ones you can take, the enhanced customization of the weapons, and of course, the fighter jet sequences that are pretty much right out of an anime like the aforementioned Macross.
The only problem I have regarding IW's campaign is that it is pretty obviously a clear cut good vs. evil storyline, with the SDF being portrayed as so over-the-top evil that it's almost comical (heck, even the quotes from them seem like they're from a Saturday morning cartoon villain). But it manages to make up for that by fleshing out the characters you are fighting alongside much better. Granted, some of the developments they get are a bit abrupt and the like, but on the whole, I really grew to care for them. That, and it has what I consider to be one of my favorite robot companions in all of gaming.
It's a shame I feel that so many people jumped on the hate bandwagon for the game solely due to the setting and thanks to Battlefield 1. Cause I really think IW needs more attention, if not for the multiplayer (which admittedly is a bit underwhelming), then for the campaign.