Most likely King's Trench
In short: It's much less crowded than Denali / Mc Kinley + offers a great winter touring / ski touring + several days of camping in high altitude / snow + great views.
In detail: Logan is the second highest peak in North America and highest in Canada. It's has the largest base circumference of any non-vulcanic mountains and the massif has eleven peaks over 5000 meters. Furthermore the height differencies between the base and the peaks are truly magnifficent, over 3000 meters. The Kluane National park, where Mount Logan is located, is also one of the UNESCO world heritage sites with huge glaciers. It's simply an extraordinary place on earth, a peak that, if any, deserves to be included in the Mammut 150 peaks project.
From personal point of view: I have looked several areas for longer ski touring and climbing trip and mount Logan seems to be a good alternative, difficult enough to be challenging, but easy enough for some one like me and my friends (who have plenty of mountain experience, ice climbing experience + winter camping experience, but litle high altitude >5000m experience). As such Logan is a good start / trial for high altitude climbing and further trips, it could perhaps be a staring point of 7-summits project.