the altimas that always get towed are 2.5 4cyl motors. i work at nissan and i see alot of 3.5 6cly (oil changes mostly). very rarely do they need anything mass air sensors have gone out with them. on 3.5 only you can replace just the sensor on prod. months from 9/03-1/04 and 8/05-10/06. i do see them come in for front motor mounts. but not very many. overall 3.5 is a good car. 2.5 is... well... uh... i dont feel like typing so much.The Mass Airflow Sensor is a prevalent issue with these cars. It can be pricey ~$500 but it's super easy to do yourself. Also, it's not guaranteed you need to. In my case it only went sketchy once and never again. It hasn't re-appeared and if it does, I know it also won't leave me stranded.
My Altima specifically has fuel line issues and hates the cold. On that note, my tow truck driver said that Altimas are one of the cars he tows the most for not starting. The day he picked me up, I was his 3rd of the day. That's pretty terrible, imo, but not an issue if you're in the lower USA.