I suspect a lot of complaints you've read elsewhere about Markins heads may be at least partly due to not understanding the product and how it was designed to be used, especially the idea of the "sweet spot".
For better or worse, Markins heads were designed to let the pan base slip when it is under extreme torque. They do not, by design, lock down absolutely. Some are bothered by it; I am not, at least with my M20. The smaller heads will hold progressively less panning torque which can have an effect on long telephoto lenses. But those lenses deserve a Q20/M20.
I've never heard of a Markins head "slipping", if slipping means the ball moves after being locked down. I would destroy my lens mounts before any of my Markins heads (including the little Q3) would slip.
I own 3 Markins heads and all have performed flawlessly for many years (my first bought in 2004). For that reason, and because I have never handled a head that performed better (for me, the way I use them), I highly recommend them. I also recognize that other people have different feature preferences and prefer other heads. I think we get a good mix of recommendations here, based on people that own various heads they are happy with.
I am the primary mod here. Because I own and highly recommend Markins heads that is what I personally talk about. To the best of my knowledge there is no "editorial pressure" here on anyone, and there is no one actively involved on this forum that has any financial interest in what head you buy, with the exception of Jrp (one of the site founders) who does pop in from time to time. If I preferred RRS heads then that is what I would recommend and there would be absolutely no hint of pressure on me to do otherwise.
All the mods here are unpaid volunteers. We have absolutely no skin in the money side of things.
The reason you sense a "Markins-centric" environment here is simply the momentum that a few active members, such as myself, can have on what people buy. As more people buy the product, and are *satisfied* (that is key here) more people recommend it, and etc.
On the other hand we have at least one active mod here (Eric) that shoots RRS and highly recommends that brand. I obviously spend a lot of time here yet I don't think the preponderance of the posts here are "Markins-centric". I think there is a very good mix of opinions, something I am grateful for and encourage.
(edit: oops.. forgot to add Ned. I'm actually outnumbered here )
Whatever the members recommend here is largely based on what they've read in the past, what they own, and how they feel about their products. If it leans toward Markins then that's just the way it evolved.
This forum does act as the primary support mechanism for Markins products purchased from the site shop. That is part of the reason you see so many Markins discussions here.
I have yet to see a low priced head perform comparably to the higher priced heads. All the higher priced heads are in the same general price level (high or even higher!).
My thinking on this is that if it were possible to bang out $100 heads in the Far East that perform as well, someone would be doing it. But historically that has just not happened. And that suggests that there is simply too much fine engineering and manufacturing involved. I've seen some hints, though, that some pressure is slowly getting put on the high priced spreads.
There is a peculiar problem with ballheads (and tripods and other support gear) in that they are NOT readily available in local shops. Plus, local shops are disappearing quickly. Because of that, it takes years for a new head to get distributed to enough people to get a feel for the quality of the product. Few of us have experience with a number of different heads and it takes more than a 5 minute field test to understand the subtle differences that can make a head superior or near useless.
I see some indication that inroads have been made in "cheap manufacturing" but it will take years to see that pan out. And the problem with low priced products like that is that those years are longer than the life cycle of the average low end product.
Even if something were to stand the test of time, by the time that happens in many cases that exact product is no longer made and we have to start all over with the vetting process. That is one reason why the old-line (expensive) makers are successful. They don't continually change their products and therefore what they do make can stand the test of time and get vetted in the market place. The changes they do make are slow and evolutionary (such as the Markins M to Q lines).
Speaking purely personally here, I respond to requests for low priced heads as best I can. But I have never handled a head significantly cheaper that did not come with a complex set of compromises, many of which are difficult to explain to a first time ballhead user.
As a result I tend not to make specific recommendations in that area because I don't want to be responsible for a bad buy. I try to explain some of the important concepts in order to guide further research.
If I knew of good $100 heads that did not come with a list of caveats I would recommend them. But I don't. I leave that to other members who might be more comfortable recommending those specific products.