Sorry this is so late! I didnt realized you actually wanted MY help, feels nice to be wanted lol.
If you haven't gotten the card already, its absolutely fine to mix gpu and mobo branded hardware, but it primarily goes on a case by case basis, for example you shouldnt mix RAM because -depending on the type- you could severely limit your performance, E.G ddr3 with ddr4 kits or issues with dual channel. but putting different branded GPUS in your system are no problem, and I actually have the MSI TRIO and its amazing. But Strix is absolutely fine as well, just go with the cheaper one as OC cards tend to only have a small increase in clock speed that its almost not worth it.
But yet again its all up to you man. I wanted performance so i went high, and thats just me, So who am i to judge? btw different third partied cards dont really deviate all too much, even in terms of reliability they just kinda add on their own cooling and maybe an OC but thats about it so don't take too long deciding as its not a big difference usually.