I have spent the last several hours researching which credit card would be the best choice for me. My main goal is to get miles which can be used for future fares. From what I've read, SPG may be the way to go, but I just want some feedback before making a final decision. If there is a card that you think is a better fit for me, please advise.

Here is some info that may be relevant. I am self-employed and work out of my home. I suppose I could get a business card if that is advantageous, although doing a quick overview of the SPG Personal vs Business, it looks like I can get 25,000 bonus miles with the Personal, but only 10,000 with the Business. Should I just go with the Personal if I go with SPG?

My monthly expenses (mostly online using my CC) are 8000-12,000. I also make most of my grocery/gas purchases at Costco (another advantage of AMEX SPG).

SLC is my home airport, with several airlines to choose from, so I'm not sure I want a card that is tied to one specific airline. I am very new to all this, so I appreciate any help you can give. If there is some pertinent information I have left out, please let me know. Thanks in advance.