Thanks for the replies. I guess the solution to my original question would be having a G&C thread and writers linking to testimonial posts in said thread.
I also don't want to start a popularity contest. I think it's helpful for the community at large to see what people like most about their favorite partners, and healthy for there to be a positive space to publicly praise people at more length than is common for the forum games/socializing sections.
Because this idea seems potentially controversial, I'd like to get feedback about it from more people/discuss the idea in greater length.
Also, I wasn't aware that O/O threads were intended to never be posted in by anyone other than the original author. I re-viewed the General Guide and the Rules threads, but didn't see a reference to that intention. I suggest highlighting it in guide, or adding that policy to the sub-forum's description/tooltip.
Edit: Re-worded a sentence that might have sounded like I was offended.
To clarify what I'm thinking of for "testimonials":
I might write with something like five (if the match % is high) or 20 (if there are a lot of misses) partners before finding one that seems like an all-around great match. Their writing style and format would be enjoyable, but - more than that - we'd get along very well and be on the same page when it comes to developing plans, manner of discussion, refining ideas, patience, etc. Most importantly (and what I'd highlight in a testimonial), the way in which they interacted and the kinds of things they did that were especially helpful or interesting would be the reasons for my public praise - things related to conscientiousness, thoughtfulness, novelty, and so on.
While I could give a few words of praise about them in a game/socializing thread, it wouldn't really do the great experience justice. And, really, if I'm going to make an at-length public post praising someone's conduct and writing, it makes sense to me to do to in a way that allows other people in the community to see what qualities/behaviors might be especially valued by others. The partner also might not be aware of how valued those qualities/behaviors are, and/or may not be skilled at describing them as part of their behavior in their O/O thread.
I wouldn't write a testimonial/recommendation for everyone I write with, and I wouldn't write one if I didn't have a lot of good things to say (concisely).
I understand that some people might feel "left out" if I don't write a testimonial about them, and that others might worry that cliques are forming. I wouldn't want either of those things. However, the same can be said for who one chooses to focus on writing with in general - as described in one's O/O thread or as actually occurs in group games or and who is chosen out of people who comment on request threads. And, unlike the "seeking"/group/request situations, testimonials provide information to the community that would be of service, and might be seen as another example of Elliquiy being a more positive and friendly forum than other roleplaying sites.
Personally, rather than viewing the idea as being about popularity or instruction (e.g. "This is what a good partner is"), my reactions to seeing partner testimonials elsewhere have been "This person/culture really celebrates good interactions. This is the kind of place i want to be." and "There are things that I can learn from this."