<p>Multiple approaches exist to write your unit tests when using Rhino Mocks:</p>

<ul>
<li>The Standard Syntax</li>
<li>Record/Replay Syntax</li>
<li>The Fluent Syntax</li>
</ul>

<p>What is the ideal and most frictionless way?</p>

Interesting question!  My own preference is the for the reflection-based syntax (what I guess you mean by the Standard Syntax).  I would argue that this is the most frictionless, as it does not add much extra code: you reference the stubs directly on your interfaces as though they were properly implemented.
I do also quite like the Fluent syntax, although this is quite cumbersome.  The Record/Replay syntax is as cumbersome as the Fluent syntax (if not more so, seemingly), but less intuitive (to me at least).  I've only used NMock2, so the Record/Replay syntax is a bit alien to me, whilst the Fluent syntax is quite familiar.
However, as
this post
suggests, if you prefer separating your expectations from your verifications/assertions, you should opt for the Fluent syntax.  It's all a matter of style and personal preference, ultimately :-)