I can't offer an opinion of "Proface or Siemens" but I do have an opinion on Maple Systems.
We have a lot "Maple System" Hmi's out in the field. They offer a tremendous amount of features for a lot less money. The programming software is FREE, and very easy to work with. Their SUPPORT is some of the best I have ever had to work with.
They have "MACRO's", Trends, Data logging, Tags, Modbus (rtu/tcp), all Hmi's are a MQTT publisher, remote access, several layers of security, Email, ETC..
In my book Maple System is hard to beat.
I've worked with iX Developer and GP-Pro quite a bit. IMO, iX Developer blows GP-Pro away. The recipes, data logging, and C# scripting capabilities in iX Developer are pretty nice. GP-Pro has scripting, but it's some proprietary Pro-Face language that leaves a lot to be desired. iX also handles text tables for multi-language interfaces much better than GP-Pro. The graphics in iX are also much more modern and pleasant to look at. GP-Pro's default buttons look like something from Windows 95 pamphlet, and tying multiple actions to buttons in GP-Pro isn't nearly as clean as iX.
I think the only reason we switched to Pro-Face from Beijer was due to Beijer's support in Asia. But, I've heard it's gotten much better in the last few years.
EDIT: However, Pro-Face's Blue software looks good. Lots of functionality, modern looking objects, adding expressions/visibility/scripting to buttons isn't a PITA. I think you can get a trial for 30 days free.
I wouldn't recommend Siemens.how's the Beijer HMI software compare to Maple system,Proface, Siemens and etc?
iX Developer creates large files, so invest in a larger HD and set up a DropBox type account if you need to send files to customers.