Here's the story: I am in a bedieved situation. I have been davening in minyan P recently but unfortunately I have to leave after shmoneh esrei due to time constraints. The benefit with this minyan is that I have been improving my level of kavanah and this minyan is conducive to that. My schedule has recently slightly changed a small amount which allows me to return to Minyan R in which I used to daven. The problem with this minyan is that it is a matzah minyan (18 minutes or less - actually it is not that fast, but is still pretty fast). When I daven there, I have no (read: zero) kavanah, but I get to stay for the whole davening.
Now, I am not looking for you to tell me that I should leave both and look for a different minyan or change my morning schedule to allow me a good minyan and to be there the whole time. I am currently not able to do that. It is either minyan P or minyan R.
So what is preferable - daven with kavanah but leave early (including missing torah reading and everything else after shmoneh esrei) or daven the whole thing with a minyan but with little or no kavanah. What is better?