I like my 1911s. The Sig 220 is a work of art, but the 1911s have always felt better in my hand. I also like the single action design of the 1911 over the double action P220.
Still, they're both great .45s. My only advice on your choice is that you should find a range that rents both, and run a box or two through each handgun. Do you like the single action or double action? Recoil characteristics? How do they feel in your hand? Natural pointability? Can you should one better than the other? If there is a possibility of concealed carry, which is more comfortable, and do you feel safe carrying cocked-and-locked? Are you familiar with the 1911 at all?
The fact that you already have a P226 and that you really like it would suggest that you should get a P220 for a uniform manual of arms. Between the 226 and 220, you have the same trigger pull, decocker, slide stop placement, etc. The 1911 would be good for variation, but the P220 might be more practical since you already have a P226.
You have two good choices and can't go wrong with either. Maybe buy one now, and budget to buy the other next year ..........