In my case I'm storing the DB on my Google Drive for now, but Keepass2Android supports many different systems, including "generic" things like WebDAV, so really anything should work.
While Keepass2Android is integrated with the syncing and will always check for conflicts (i.e. check for latest version before saving), the same isn't necessarily true for the desktop client. But since I rarely edit from both devices at the same time, anything that syncs to the Desktop in a somewhat realtime fashion should work just fine.
And for the few (long ago) cases where updates were overwritten, the "previous version" feature of Google Drive was god-sent! (And KeepassX can simply merge the old overwritten version into the current one and you'll get the correct merge).