I'd go with SRAM eTap over Di2 but I'd go for Force.
I built a bike a few years ago with Ui2 - worked great. Then I converted a previously mech bike over to electronic shifting and the obvious choice, because of no internal wire routing, was eTap. I liked it *so* much, when eTap Red went on sale, I bought the group, sold the Ultegra Di2 group and installed eTap. My wife also got an eTap Red set up and then a 1x AXS system on her new gravel bike.
For me, there is no question this was the right answer. I live in the frozen north and I do a lot of riding when it's cold. The double paddles on the Shimano shifters are impossible to get right or feel well with real winter gloves and are a nonstarter with mittens. Etap has none of those issues. It's also a lot cleaner installation and it's much better for when we disassemble our bikes for travel. A side benefit is that an entire group installation is about an hour even if you've never done it before. It's ridiculously simple.
Given a choice on a new bike, it would be - without question - AXS eTap for me. Pick your group, but eTap. Been there, done that.