Redmine

As Sebastian Paluch told in Feature #16067-5: Generic New Issue page:

The only issue with current solution is that when navigated to https://redmine.host/issues/new the issue Project is defaulted to
@issue.project ||= @issue.allowed_target_projects.first
This is not ideal, as we really need user to choose right project.

This is a small change to replace the oldest created project with the first alphabetically listed project.

diff --git a/app/controllers/issues_controller.rb b/app/controllers/issues_controller.rb
--- a/app/controllers/issues_controller.rb    (revision 41804:94cb08cd65eb27ef693ca8144836553a3c3183ab)
+++ b/app/controllers/issues_controller.rb    (revision 41804+:94cb08cd65eb+)
@@ -571,7 +571,7 @@
     end
     @issue.project = @project
     if request.get?
-      @issue.project ||= @issue.allowed_target_projects.first
+      @issue.project ||= @issue.allowed_target_projects.order(name: :asc).first
     end
     @issue.author ||= User.current
     @issue.start_date ||= User.current.today if Setting.default_issue_start_date_to_creation_date?

Another suggestion may be replacing name by identifier.
This gives admin the ability of changing the order of projects for being selected as default.