I would recommend staying with the same brand of speakers and even the same model types. If you use different brands and models, the speakers won't match and the tone will be different. You might not notice the sound difference though.
It's not a hard and fast rule. You don't "really" have have all of
the same brand. The only case where it would be totally necessary
is in the case of a 5.1 surround sound system. In that case each
channel must be timbre matched.
That choice becomes even more obvious when it comes to subs. You
definitely don't have to have subs from the same manufacturer as
Feel free to mix and match as per your own sound preferences.