Looked at & tried several apps, & wanted to share a few quick notes.
The practical reason for HDR photos, is for those shots where you can't capture the complete dynamic range that you see in a single image. Probably the classic example, where you're told Don't Take The Picture, or at least Use Fill Flash, is someone at the beach with a bright sun behind them. It goes along with the rule that the photographer should have the light behind them. The reason is that you or the camera can only set the exposure for the bright background, leaving your subject dark in shadow, or the exposure can be set for the subject, and the background will be blown out, way too bright to see any sort of detail. With HDR you'd take both shots, combining them in software. Colin Smith has a great example of when to use HDR here, though the bulk of the tutorial has to do with Lightroom, so you may [or may not] want to ignore it.
photoshopcafe[.]com/Lightroom-HDR-tutorial
Under more controlled conditions [lighting], using HDR will most always not make a difference -- other than you having to do more work that is. And while Colin came up with a dramatic example, many [most?] shots where HDR will help won't see that huge of a difference. But marketing folks never have let something like a few facts get in their way of selling you something... apps like Franzis HDR focus on all the special FX you can use, regardless whether anything's HDR or not. Now there's nothing wrong with using special FX -- knock yourself out -- but please don't confuse that with the basics of HDR, when & why.
If you ignore the more sensationalist aspects of Franzis HDR, their newest HDR 2018 Pro seems to have more settings & fine tuning controls than anyone else, giving you all sorts of control over the merging or 2 or more photos. ON1's new Photo Raw 2018 lets you do HDR, but it wouldn't work with just 2 shots, while everything else would. PaintShop Pro 2018 is pretty basic, but it does give you some controls. Adobe's Lightroom basically lets you turn 2 auto features on/off, & set one of 4 levels of de-ghosting -- that means trying to fix places where the shots are different from each other.
Lightroom is unique in saving your HDR merged image in Adobe's RAW .dng format, which potentially solves some sticky problems. If you've got RAW images, each image includes all the sensor data that was available, RAW, because that data hasn't been turned into a picture yet. Turning RAW data into a picture is a lossy process, meaning some data gets thrown out. The idea is that you might be able to do a better job of turning that data into an image than say software, or a camera. So lightroom lets you create an HDR image and control to a very large degree how it's turned into a picture you can view & share. The downsides are that HDR .dng image is large, & if you send it into Photoshop for finishing, and save that P/Shop file, it's going to be HUGE. An image that winds up as a full size .png at ~12MB came from a P/Shop file that's over 250MB. You're working with loads & loads of data.
While the other apps will accept RAW images, using them for HDR, when you're done you have a picture -- it has more than the usual amount of data, but it's still a picture. What you can do with that picture [vs. RAW] is more limited. And you can't process your RAW images beforehand. And that may be perfectly fine.
How much you want to work hands-on with any image is up to you. You can get perfectly good, even great images without spending lots of time in the details. But there's another thing that can be nice about shooting RAW images -- those RAW files are read only. So if you bring them into Lightroom or DxO Optics or Aftershot etc., all the things that you do to those photos is more-or-less recorded as a script that's used when & if you turn a RAW image file into a picture. You can go back 6 minutes, or 6 days or 6 years later, and fully edit that script, changing your mind about anything. And your original RAW file is still untouched. That's cool, & Lightroom's RAW HDR files are cool, *IF* you think that being able to revisit your images is something that might be useful. If when you're done, you're done, it doesn't really matter a whole lot.