Thats a bit of a loaded question. A little background on me, I currently manage about 4k Windows 5070s and about 50 ThinOS with WMS. Before that I managed 4k ThinOs using WDM.
To start you need to consider your companies expectation and roadmaps and make sure your management server and hardware can align with that. I’ve looked at IGEL years ago but ended up staying with Dell due to existing hardware we carried over. However, if you plan to replace those machines at all it may not be a bad idea to look into IGEL.
One thing you can try is reaching out to IGEL sales and state your intention of using them. They can help with providing you with a test machine you can use to deploy a temp environment to see if they fit your need. Its extra work but it does help you see if the IGEL experience is worth the switch.
Wish I could give you a more specific choice but there’s too many things to consider to just pick one. You should consider also setting up a WMS test server and add a few devices into it to see how it fairs. You can use the free version for most basic setups. Compare it with IGEL and see how you feel about support and ease of management.