Everything of this is just my knowledge, and it may be wrong at some things, so take it with a pinch of salt... I'd wait for someone else to give his opinion as well before considering this a trustable answer
Quality-price wise, the best you can get right now is either a R9 280x or a GTX 770. Depending on the budget you may get a notch down (270x/760), but anything lower will probably not meet your expectations, nor last long enough.
As per partner brands, the best kinda shifts with every model released.
I've heard Sapphire has the best pieces if you look at the "Toxic" models (featuring Tri-X coolers which keep the card and the VRMs decently cool with massive factory overclocks...), but I guess ASUS and XFX are good to go too, followed up by MSI being the noisiest of the bunch (if you care about fan noise).
Last, but not least, yes, you get tearing with every card out there, and artifacting as well with a smaller number, but that depends on your game settings, on its requirements and on your resolution. 1080p on high details (or max on some) can very well be run at +60Fps by a R9 280x, but you might get some dips with a 270x, causing tearing or 30-Fps capping if you got V-Sync active.
It pretty much depends on what are you willing to sacrifice, whether it's image quality or framerate