Hi, I've also done this trip a few times and I agree with the post above that it is very nice to do it all the way down to Trelew and then cross towards Esquel through RN 25. However, this adds lots of km and money.
A more direct way and nicer way than going through La Pampa province, as first suggested, is to take RN 3 and RP 51 to Bahia Blanca, and then RN 22 to Neuquen and then RN 237 to Bariloche. This is just 100km more than going through La Pampa but the landscape is more interesting.
For example, you could stop in Sierra de la Ventana, which is a lovely resort in the hills (sierras) of the southern Buenos Aires province. This, together with the area of Tandil, is the only area in the province that has little mountains (1200m) and the landscape is quite pretty, check some photos on google map. That's 600km from BA and then you have 1000km to Bariloche. So, provided you start early you can get to Sierra de la Ventana early afternoon, check it out and then the following day do the rest.
As you take RN 22 and you pass the town of Chelforo, you will enter the Alto Valle of Rio Negro that is the most important fruit production area in Argentina, and now are also producing wine.
Another option instead of stopping in SDV, is to do it in Rio Colorado or Choele Choel. But these are pretty sleepy towns. The good thing is that they are right at the middle of the trip, so its around 850km for each half.
Just a thought hope it helps.