Can't say for horde as I don't use it. But if you can afford some time to get SOGo running, go for it. It has (optional) EAS support, but the native carddav/caldav support is very reliable, and works very well with iPhones, iPad, MAC OS X, Thunderbird, Evolution (native support for them), and also on Android (with Caldav-sync and carddav-sync app), and even on Outlook (With OutlookDAV)