Great Northern Line is very reliable. My dds have used it twice a day for over six years to get to school and it very rarely lets them down. Only once in that time did it fail them completely and that was when one of the stations was struck by lightning.
Hatfield is up and coming. I predict house prices will increase above the national average as it has so much going for it. Great shopping (Hatfield Galleria), Great motorways A1M and M25, good primary schools, easy commute to QE and DAO and excellent commute into Finsbury Park where a spiral staircase leads you to Victoria and Piccadilly lines stay on the train to Kings Cross with a plethora or buses and tube lines or Moorgate, one short escalator to the Northern line. Two different overground train services, one going to Moorgate and one to Kings Cross.
Brand new station with number recognition car park, so no returning to the car with tickets and £2.50 all day on Saturday and Sunday for day trips to London.
All considerably cheaper than the neighbouring towns of WGC, St Albans, Hertford Brookmans Park and Potters Bar.
Great local secondary for girls, Bishops, but one downside, co-ed underperforms and hard to get into local single sex boys schools.
For those who are prepared to work hard to get into QE or DAO it is great bang for buck! DG