Obviously not been a NYC Firefighter, but a fireifghter in London, UK, i can only say what i imagine to be the case.
I wouldnt have thought Hazmat would be a sought after company, howver if one had desires to get into Hazmat then i amagine 'knowing someone' can only be an advantage, simmilarly rescue, and squad companies, which i would imagine would be more popular for guys who have done time on trucks and engines, knowing a member or officer, and having your name mentioned in the kitchen around the table at the right time can only be a plus im sure..
I would have a guess at companies guys want to go to from proby school or trnasfer into, and my guess' are;
E58/L26
E62/L32
E75/TL33
E290/L103
Im not sure about the busy midtown companies, are they sought after postings?? E1/L24, E65 and E54/L4, busy but not much fire... the serving members will probably be bale to correct me.
In London, the stations sought after are Soho, in the smack centre of the theatre and clubbing and nightlife district, and ridiculasly busy at times, ( i have done nights there as a ladder driver, and not seen the inside of the station the whole night, its quieter now than it used to be, but still busy), Paddington, Tottenham and Dagenham.
JT