I’m still using Nuke Indie to crop the left and right sides of the image so I can render it at a larger size. Then, I’ll use Fusion Studio to stitch it together. This takes longer than just rendering the final output directly and this is the big issue.
It’s more like getting your feedback and learning more about Flare as I try it out during trial period.
Things I like:
Nuke
Fast, useful gizmos and tools from Nukepedia. Das grain. Simple and logical node view. Easy to mach blacks and whites with few clicks. Huge learning source.
Fusion
Free versions from v9, at least for now.
Flare
Built in Match grain so far. Still early stage of trial.
Price:
Nuke Indie / 449 euro + VAT (1 year)
Nuke / 2989 euro + VAT (1 year)
Fusion Studio / 295 euro + VAT (Singe payment so far)
Flare / 2028 euro + VAT (1 year)
Biggest issues: at least for me
Nuke Indie / Nuke
Nuke indie
Resolution limitation and limited phyton.
Nuke
It’s a stripped-down version of the more expensive NukeX, with fewer features.
Fusion Studio
Not intuitive node flow and when used on same PC and Mac, it is slower than Nuke to process when doing similar tasks such as basic green screen keying over new background.
Flare
I’m not sure yet. I need to try it out more. I think there are the least amount of trainings or resources available on the web.
Oh, one thing comest my mind. Project management. With Nuke and Fusion, comp file is saved where ever you want under project. It is easy to locate, move and copy. With Flare it creates some kind of managed data base without old familiar file structure. What happens if it breaks?
And matching blacks and whites. How can I mimic super easy Nuke Grade node?
Community:
Nuke Indie / Nuke
Non existence for Nuke Indie community on Foundry forum. Not sure about Nuke forum.
Fusion Studio
Good community. Some are very helpful, some are harsh…
steakunderwater forum
Flame / Flare
Seems like very friendly and helpful community here. 
Summary:
Nuke Indie
As I mentioned before, the resolution limitation and limited phyton are deal-breakers for me.
Nuke
The price is a bit high, and it’s missing some features. I could always replace the missing features with other apps, but that would definitely add to the cost. Also, I’ve had a really bad experience with Foundry’s sales team. I’ve reached out to them multiple times to ask about switching from Nuke Indie to Nuke, but they’ve ended our email conversations multiple times during the middle of our discussion.
Fusion Studio
Feels slow. I’m not sure what’s causing the issue. When I cache or render, it doesn’t seem to be using the full power of my CPU or GPU no matter if it’s PC or Mac.
Flare
I need to try it out more.