It depends, if you really need TTL, then of course buy those from your own camera brand. but if you dont, even 3rd party flashes would work well.

people always say that 3rd party is bad la bla bla bla but keep in mind, you are paying less than half of the price for the equivalent 3rd party flash. don't expect them to work like magic.

i used a yongnuo 560 II for 2 years already, gives me no problem at all.