I’ve got a blood orange tree (I think Arnold) and that made some interesting marmalade.
I’ve used store bought Valencia and Navel oranges with reliable success, but they’re nothing interesting.
I gave a bunch of my home grown Meyer lemons and Tahitian limes into marmalade which was quite interesting as the peel did most of the work (tasted a bit like a lemonade cocktail on toast).
I’ve also got a Minneola Tangelo tree, which I’ve always thought would be interesting to try as a marmalade, given the aroma of the peel is a bit different, and the quite tart flesh might need a bit more sugar and setting agent (if you’re using it) given the higher acidity, but every winter we always end up eating all the fruit so don’t have any left over.
Not sure how adventurous you want to be. I’ve got a half finished jar of ginger marmalade which is pretty different, a bit of a firey pepp up in the morning or adds a bit of razzle dazzle to a plain scone (I think called a biscuit in the USA?).
Let us know what you end up trying!