Neither. I vote ipod touch if you are going to get something but I think 19 months is way to young for such an expensive toy. I bought my oldest a refurbished ipod touch when she turned two and put an otterbox on it. I spent less than $200 and a year later its still in excellent condition. Then get yourself an ipad mini if thats what you want.
I wouldn't buy one just for my kid and he's almost 4. No way I'd buy one for a 19 month old.
My son just shares my things for the very limited amount of time I let him use it (usually in the waiting area at the doc office or other place where he MUST sit still and quiet for an unknown amount of time). Hell, even then a few dinosaurs and a little attention from me does the trick without any electronics.