It depends on what you can afford. When I built up my Litespeed last year, I did a lot of thinking. I have R7000 105 on my Canyon and it works great. And I also considerered a mixed groupset, because I'd bought a 7410 Dura Ace crankset to complete a 7410 build on it originally (recreating the BIke Of My Dreams from the mid 90s) but I wanted/needed lower gears than 53/39 x 12-25. In the end I decided to go for a full R8000 Ultegra groupset because 1) I could afford it and 2) I wanted the best for the Litespeed. And it's been great! It shifts just a hair better than the R7000, and I don't have any "Gee, what if I'd gotten the Ultegra?" thoughts. If I hadn't gotten a bonus at work, I'd probably have gone for the 105 and been okay with it, but I did, and I'm happy with it. In fact I have to keep reminding myself to ride bikes OTHER THAN the Litespeed!
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