My conclusion about type compatibility is that trying to make a rationalistic argument as to what types are "best" for each other is a fool's errand.
There are too many complexities (MBTI type, enneagram type, instinctual variant, health level, alignment, values, goals, beliefs, etc.) to do it.
Thinking that you can match two types from just one of these system is ridiculous.
That being said, I think there is value to learning the systems, and I think there are definitely tendencies based on type.
I've definitely had a tendency for dating EFPs throughout my life; but, that being said, I'd be open to dating someone of any type, really.
I think there's something to most of the major rationalistic theories (INTJ<->ENFP, INTJ<->ESFP), but I think experience speaks for something as well.
This site, for example, say they base their recommendations off observation/experience (i.e., empiricism), as opposed to rationalist models.
And, as such, they have drastically different recommendations for whom INTJs (and just about every type) should date.
For INTJs, they recommend: ESTJs, INTJs, ENTJs, and ISTPs; next: INTP, INFJ, INFP, ENFP; last: everything else
Then again, maybe they're full of shit, and have no idea what they're talking about.
This site has interesting stuff about enneagram marriage correlations.
But, then again, if you meet someone of a enneagram type who's supposedly not correlated with your enneagram type, and you get along with them great, are you gunna let a supposed negative correlation between your types (according to this website) stop you from pursuing that relationship? I mean, frankly, that seems like a retarded course of action to me.
So, yeah, I've come to the point where I don't really have any hard conclusions on what type should be with what type.
I don't think that searching for that answer, though, has been a fool's errand -- quite the opposite in fact.
While I may not have any hard conclusions, I do feel like I've learned a helluva lot.
I think I'm far better-equipped now to understand what's going on, and whether I want to be with somebody, than before.
And, while I don't have any hard conclusions, I do think something along the lines of an e2 or e9 (I'd arrived at this hypothesis before I saw the data from that website), probably sx/sp (I'm sp last, and, honestly, I think it's probably important that at least on person in the relationship have some frickin sp), maybe EFP, maybe NTJ, maybe IFP, or even IFJ or NFJ, would be my most preferred/most likely match (but, tbh, I'm probably open to any MBTI type), but, perhaps most important, is that they are mentally healthy (high enneagram health level), and that, however we might be, we have compatible goals/desires/values, and will have the goodness of spirit and strength of will to make the good times as plentiful/abundant as possible, and the emotional, mental, and spiritual fortitude to work through the tough times (which will inevitably arise).
I dunno, that last part sounded cheesy, but I think it's true; I feel like I just said something that [MENTION=6109]Halla74[/MENTION] would write.