Well the good news is that, in this price range, with the reputable online brands that have been suggested (Aperion, Ascend, Salk, Philharmonic) you're not going to be getting a "bad" speaker no matter which brand you choose!
But at this price, you also most certainly want to make sure that you are getting the very best choice for YOU and your room and setup. There are most definitely some audible differences between all of these speakers. But it's awfully hard to say that any of them are outright "better" than any of the others. We're at a level here with any of them that they are all objectively quite "good" just in terms of the basics of good sound reproduction. At this price point, it's all about the little details that one listener might
prefer over another.
I can sympathize with living outside of the US and needing to basically make this purchase once and not really having a convenient or inexpensive way to return ship most of these speakers if you don't like them. But I have to say, with this kind of money on the line and all of the choices being objectively "good", but still having definite differences in sound, you really do need to be able to hear and compare them for yourself. We're all going to have our favorites here, so you're not going to find a "clear winner" if that's what you're hoping for.
My suggestion: if you've already narrowed it down to just two brands in Ascend and Aperion, I would recommend that you order just the center speaker from both. That way, you can listen to the two centers head-to-head. You can compare them and decide which one you like better. Then return the "loser" and order the rest of the matching speakers for the "winner".
While you will be out the shipping cost of the "loser", at least it is only one speaker. I think that would be money well spent so that you can feel far more confident in your choice. Your personal preference, your room acoustics, your setup and placement; these are all things that no one here can really replicate. You have to hear it for yourself in a case like this.
Hope that helps