Tower appears to be between GitKraken and SourceTree in detail, but gave two scary error dialogs when attempting to merge resulted in a conflict. Doing the same in SourceTree just worked and showed the conflict in its handy file view that's always visible (unlike Tower's mere "Merge branch 'X' into develop" message when the commit is selected).
Both GitKraken and Tower lack the commit hash in their history overview, requiring one to select a commit to see it.
GitKraken appears to be the only Windows 10 Git GUI suitable for night shifts, but like Tower is only free for 30 days, unlike SourceTree.
Thank you for your feedback! We'd be grateful if you could get in touch via https://bit.ly/towersupport with details so we can make sure this feature works as intended!
I understand it's easy to have everything going through a single issue tracker, but right now i can only suggest to add more automated tests for merge conflicts.