I would definitely wait for the new one. The 12 Antares is still a great reel in quality and size! By that i mean its bulky and heavy, i´ve seen a pic of the new 19 next to the 12 and it looks way smaller, plus the new one has the latest version of the SVS brakes wich i prefer to the original one (less need for constant lubing and less noise on the cast).
With that being said... if you find a 12 one for a great price, now that´s being descontinued, then in that case yes... it could be a good alternative, but even in that case i think i would go with the 19.