So, which server should you use? Which is best?
Obviously, there's no right answer to that question. Every team has different needs, and the different servers all represent different sets of tradeoffs. The Subversion project itself doesn't endorse one server or another, or consider either server more 「official」 than another.
Here are some reasons why you might choose one deployment over another, as well as reasons you might not choose one.
Quick and easy to set up.
Network protocol is stateful and noticeably faster than WebDAV.
No need to create system accounts on server.
Password is not passed over the network.
Network protocol is not encrypted.
Only one choice of authentication method.
Password is stored in the clear on the server.
No logging of any kind, not even errors.
Network protocol is stateful and noticeably faster than WebDAV.
You can take advantage of existing ssh accounts and user infrastructure.
All network traffic is encrypted.
Only one choice of authentication method.
No logging of any kind, not even errors.
Requires users to be in same system group, or use a shared ssh key.
If used improperly, can lead to file permissions problems.
Allows Subversion to use any of the numerous authentication systems already integrated with Apache.
No need to create system accounts on server.
Full Apache logging.
Network traffic can be encrypted via SSL.
HTTP(S) can usually go through corporate firewalls.
Built-in repository browsing via web browser.
Repository can be mounted as a network drive for transparent version control. (See 自動バージョン化項.)
Noticeably slower than svnserve, because HTTP is a stateless protocol and requires more turnarounds.
Initial setup can be complex.
In general, the authors of this book recommend a vanilla svnserve installation for small teams just trying to get started with a Subversion server; it's the simplest to set up, and has the fewest maintenance issues. You can always switch to a more complex server deployment as your needs change.
Here are some general recommendations and tips, based on years of supporting users:
If you're trying to set up the simplest possible server for your group, then a vanilla svnserve installation is the easiest, fastest route. Note, however, that your repository data will be transmitted in the clear over the network. If your deployment is entirely within your company's LAN or VPN, this isn't an issue. If the repository is exposed to the wide-open internet, then you might want to make sure the repository's contents aren't sensitive (e.g. it contains only open-source code.)
If you need to integrate with existing identity systems (LDAP, Active Directory, NTLM, X.509, etc.), then an Apache-based server is your only real option. Similarly, if you absolutely need server-side logs of either server errors or client activities, then an Apache-based server is required.
If you've decided to use either Apache or stock svnserve, create a single svn user on your system and run the server process as that user. Be sure to make the repository directory wholly owned by the svn user as well. From a security point of view, this keeps the repository data nicely siloed and protected by operating system filesystem permissions, changeable by only the Subversion server process itself.
If you have an existing infrastructure heavily based on SSH accounts, and if your users already have system accounts on your server machine, then it makes sense to deploy an svnserve-over-ssh solution. Otherwise, we don't widely recommend this option to the public. It's generally considered safer to have your users access the repository via (imaginary) accounts managed by svnserve or Apache, rather than by full-blown system accounts. If your deep desire for encrypted communication still draws you to this option, we recommend using Apache with SSL instead.
Do not be seduced by the simple idea of having all of your users access a repository directly via file:// URLs. Even if the repository is readily available to everyone via network share, this is a bad idea. It removes any layers of protection between the users and the repository: users can accidentally (or intentionally) corrupt the repository database, it becomes hard to take the repository offline for inspection or upgrade, and it can lead to a mess of file-permissions problems (see 複数リポジトリアクセス方法のサポート項.) Note that this is also one of the reasons we warn against accessing repositories via svn+ssh:// URLs—from a security standpoint, it's effectively the same as local users accessing via file://, and can entail all the same problems if the administrator isn't careful.