What really matters is your goal. What image do you want to create? You haven't said anything about that.
a pro's tool ain't your tool, necessarily
tool of HDR pros
A "pro" chooses the right tool to get the job done. Pros might choose to use anything between a large format camera, 35mm flagship DSLR and a Polaroid camera for a paid job. Are you shopping for an arca swiss now just because of that? Certainly not. Come up with your own requirements, they will allow you to find the tool that you really need (and not the one you want) Maybe your goal will make you use the same tool that a pro uses, but that's not why you are using it.
Also note that it might take a certain amount of skill and/or experience to achieve a certain effect with a tool. If you only shoot jpeg and switch to RAW, "because the pros use it", you will be disappointed by how dull the RAW images look. This is until you realise that the reason to use RAW is to have more possibilities when editing and these possibilities are what gives it the advantage over jpeg.
high quality HDR images [...] image quality
Honestly: forget about this metric. HDR is one of the, if not the single most opinionated field of photography. An image that's an "awesome" HDR for somebody, might be the worst crap ever for the next guy.
what HDR is
Sadly, HDR became a bit of a buzz word. There's a lot hiding underneath that isn't even HDR, but is understood as part of that. An HDR image has high dynamic range. And whatever you think you have seen or people told you that you have seen: you have never seen an HDR image. No monitor can display an HDR image.
RAW files have more bits per channel than the general monitor can display. It is nice to have these few more bits of data, which allows for more flexibility when editing the image into a file format that eventually can be displayed with fewer bits per channel.
All that HDR means is to add even more bits, by combining many files. This is more or less a set algorithm.
what is labelled as 'HDR' but is actually more
So what are those images then that are supposedly HDR but are not? As mentioned above, you have to lower the bits per channel so that a monitor can display them. This can be done in many different ways. Basically speaking, the goal is to take the huge amount of data into account and somehow stuff it into less bits. This process is called tone mapping.
conclusion: what's generally referred to as HDR, is actually two steps:
- creating a "super" RAW file that has even more bits per channel
- using tone mapping to reduce those bits again to be able to display the image, there are many different algorithms to this, each possibly with several parameters to tweak it.
doing HDR (+ tone mapping)
And this is where opinions are starting to be different. There are two approaches to the creation:
- the "16bit" approach: This is really about the tone mapping. What algorithm to use and what parameters to set. This is often used to achieve an overprocessed look. Colors and textures are exaggerated, which gives an aesthetic that can often be found in computer graphics (they also use HDR). The resulting image is heavily influenced by the post processing. Those that do not like this type of "HDR" describe it with some synonym for puking, which according to them led to the creation of the "artwork".
One of such bad example from wikipedia here:
The wikipedia article on tone mapping is spot on:
Many people find the resulting images attractive and these effects to add an interesting new set of choices for post-processing in digital photography. Some people believe that the results stray too far from realism, or find them unattractive, but these are aesthetic judgements, and often concern the choices made by the photographer during the tone mapping process, rather than being a necessary consequence of using tone mapping.
I have no experience with photomatix, but this approach is where it truly shines, because it offers many different tone mapping algorithms.
- the "32bit" approach: this is putting the emphasis on the HDR part. The center piece is the creation of a "super" RAW file that has 32bit. (This may or may not happen in the 16bit approach, but it is not a distinct result.) And then you simply apply your regular RAW processing to it. The results are often more photo realistic. You often do not recognise an image as being "HDR". It's like having a camera from the future that has a higher dynamic range built in. LR works great for, because it is a RAW processor, which allows to integrate the processing of "super" RAW files seamlessly.
choosing the right tool for the job
As this is such an opinionated field, the generally best advice for you becomes even more important: Download a trial of both tools and try them for yourself.
The tools you mention vary a lot in their functionality.
- LR only recently (in version 6/CC) got the merge to HDR feature. It is really only doing the merging process: Give it the bracketed exposures and it gives you a "super" RAW file. It's up to you to use the photo manipulation features from LR to get yoru desired look from that RAW file. LR does a lot more than that in terms of photo organisation and raw editing. It's worth checking it out in its own right, not just for HDR (+ tone mapping).
- as mentioned, photomatix provides different tone mapping algorithms. If you are thinking about achieving your HDR results in terms of tone mapping and not in terms of RAW editing, it is probably the better choice for you. Photomatix is available as a plugin for LR.
Just to be clear: you can create photo realistic images in both programs, just as you can go the over-the-top heavily processed look in both programs. Again, it all depends on what image you want to create.