Good question, I tried systemd first for an entire day however I have a mix sshfs and rclone remotes. The premise of using systemd to manage sshfs mounts is fundamentally flawed. Fuse is a userspace utility and systemd does not allow --user units to automount on demand, root is required. systemd offers very basic options when mounting remote drives.
This has several implications such as you cannot use your .ssh/config file, you can also not use encrypted keys with passwords as the root user has no access to any user environment such as any ssh agent running which can supply the password.
autofs also mounts in root however it is much more flexible and scriptable and has the possible to access config, userenv and ssh agents. autofs also handles the mounts much better when the system needs to suspend whereas systemd often hangs.
It works great for sshfs and apparently it also works for rclone but I can't find any documentation on the basic syntax. I think according to this post: Example for rclone 1.57 together with autofs (without rclone-mount-helper-script) that -fstype=rclone is correct once your create the ln however my basic example still doesn't work:
/etc/auto.master:
/mnt/rclone /etc/auto.rclone --timeout=15 --ghost
/etc/auto.rclone
rclone -fstype=rclone,config=/path/to/rclone.conf,allow_other,id=1000,gid=1000 :remote:
When I systemctl start autofs autofs created the rclone mount point but doesn't mount anything. I don't see any errors in the journal either it just silently fails.