Both are pretty good. Some more vrm headroom on a Crosshair, but not huge.
As you probably already saw, a Crosshair is NOT cheap.
But they are very good, with a ridiculously tweakable bios.
Ask yourself this.
Are there any feature on the Crosshair that the Strix doesn;t have?
Can I live without these features?
If not, are they worth the extra money to you?
If yes, buy the strix, save a few bucks, and be happy.
Buildzoid analysis of the Crosshair 7 leads him to believe it is overbuilt power delivery wise, possible to support more than 8 cores in the future on the AM4 socket.
If this matters to you, some research is needed for you to decide.
For your stated use, I'd get the Strix, unless the price difference isn't a deal breaker for a Crosshair.