Call me crazy, but I do use both, Simbrief and PFPX - in parallel.
The nice thing about Simbrief, it automatically calculates a good Cost Index for the cruise - something, you'd have to be guessing in loops over at PFPX (or did I miss any special setting at PFPX that can do so?). Furthermore, it has a variety of different routes available that you can choose from.
However, many times, I catch myself not being happy with those provided ones, so I revert to PFPX and copy of the many routes I created myself into Simbrief, i.e. I found that CPA uses a much northerly route on their flights to Europe almost overhead Beijing (!), than what's usually provided over at Simbrief.
Whenever I need to create a route by myself, I do that with PFPX.
Nice thing of PFPX, if you have several routes available for a flight, you can select them all (or just a few) for compiling the OFP and by that you can choose the route with the least time and/or fuel requirement - sure, the calculation time gets longer, but the feature is really nice! So with that I choose the route to fly for the leg.
I operate on a system of 5 PCs, 3 for PSX, 1 for Scenery, 1 for Flight Planning and Navigation (Charts). In PFPX I have set all the various folder locations on the cloud, for the PSX-route file, the P3D route file, the XP11 route file etc. With 1 click on export, it directly stores the respective files. Some addons can handle the cloud location, some I do need to manually copy, but I can accept that.
Another thing that speaks for PFPX, I have bought several real world schedules from over at VA Systems, that can be downloaded in PFPX format and imported into it. So, if you want to follow those schedules, you just look them up at PFPX, select the flight, and it copies some of the data incl. DEP/ARR times into the planning (sometimes buggy though, as the arrival time and thus the flight duration isn't correctly transferred).
Big disadvantage of PFPX in my opinion (besides what has already been mentioned by fellow members before), the North Atlantic Tracks are part of a paid annual subscription, whereas on Simbrief you don't need to worry about that. Same for Notams.
And, besides the bug in the scheduling-thing above, there are a few bugs with PFPX, that probably won't ever be solved.
For PFPX you can choose from the magnitude of performance files by Steve Bell (thanks again for that, and for keeping them updated all the time!!!) and with a little time, you can create your own performance files - for example, an ER-variant with the RollsRoyce Engines - never built, and not originally available on PFPX, but on PSX. There's a chance of uploading a JSON-format Performance File into Simbrief - never done that...
TOPCAT, I believe there's really no way around it. If I remember correctly, even BACARS relies on you having a valid TOPCAT license. In conjunction with PFPX, you can have your TOPCAT calculations done directly in PFPX.
Downside of TOPCAT, you can't fully work with ER-Models as there's no way to set the MTOW to 412t. So, for any TOW above 396t you'd have to manually workaround it though, by having it "print" a runway table. That can go up to 430t and you would guesstimate your derates etc.
I was having high hopes for the ProjectFly V4 which was supposed to be a comprehensive tool with use of real world systems for flight planning (?). I just realized it's out since last June, gotta have a look at that. An earlier version V1 and V2 utilized Simbrief for the OFP generation.
So, the actual used OFP I create with Simbrief, but for route creation, manipulation and export and for schedule finding I use PFPX. And TOPCAT.
Best Regards,
Sebastian
