My aunt lives in Upminster. I can?t speak for the other town but will give you an overview of what I know of the place over the years from visiting my cousins there and a little about the schools.
Schools - The area has good schools, as has already been said above, just to add to that Sacred Heart of Mary School is decent. I just looked at the website and the founder of the school was called Madame Appolonia Pelissier-Cure and a later sister was called Sister Alcantara who died at 103 ? what names! The sisters are said to have contributed a great deal to the good deeds of the communities of Upminster and Hornchurch. There is also a William Morris and Burne-Jones connection with the convent?s architecture.
Coopers School is supposed to be good for the sporty. Pre-school, there is a Montessori in the old Harwood Hall and A small handful of children also travel to the excellent independent day schools in London ? they seem to travel back safely from swimming/hockey/tennis matches despite wearing distinctly different uniforms. There are also nearer ndependent schools such as Brentwood School, Bancrofts and New Hall School.
About the area, Upminster has a Waitrose, Marks & Spencer Simply Food, an old department store called Roome's Stores and a 200yr old windmill on the hill!
Travelling time to Fenchurch Street Station/Tower Hill is under 25minutes. If I remember correctly, you can do this by British Rail or Tube. You can also swap over from one to the other at Barking or West Ham stations, helpful if there is any problem on one line. If you have someone in your household working in the City or Canary Wharf, it?s very helpful to be on the East side of London for speed of travelling.
One of their neighbours works in Green Park, the auction house area of London (W1) and by changing at West Ham, they can be there in under 35minutes on the Jubilee Line which is pretty good going. The District Line runs from the West side of London (Richmond, Wimbledon and Ealing and goes through Earl?s Court, Sloane Square, Blackfriars and Tower Hill amongst others, ending at Upminster in the East).
If you or another household member will be commuting to London, check out the annual season ticket costs and compare it with Harpenden, as it is easy to overlook factoring it into the cost of moving to a location.
Leisure - Upminster is a safe area with many restaurants, a Pizza Express, Costa Coffee and a number of pavement cafes. St Laurence Church is at the crossroads in the middle of town (famed for being the location of the discovery of the speed of sound). For the studious and curious , there is a large, two storey library (that hasn?t yet been renamed an ?Ideas Store?!) next to the park in the centre of town. There is an Equestrian Centre with Livery at the North end of Upminster and also a flying school in the surrounding countryside.
Property - Hall Lane has large, turn of the century (20th) houses, many of which face the golf course on a hill with rolling views over the Ingrebourne Valley, it has a 500yr old club house and a bowls club (if you?re swayed by sedate activity) and an old property called Upminster Court. The Fairway and the North end of Upminster has good quality houses too ? with 4 bedroom houses ranging from £600k - £1.5m. The majority are solidly built 1920s/30s houses but there are a few Art Deco and older houses. Parks are numerous, one is in the centre of town with tennis courts, opposite the shops and the Clockhouse Gardens in St. Mary?s Lane, next to Waitrose, is a calm place to take children or just to sit and muse.
Nearby Locations - Hornchurch is the next nearest place - it has a swimming pool and leisure centre and the Queen?s Theatre for plays, nearby there is Emerson Park (multi-million pound bling houses), Gidea Park and Great Warley (which has a good Ski and Snowboard centre) as well as Shenfield ? all very good areas that include the more quirky, unusual houses that are well over £1m. There are historic pubs such as the Huntsman and Hounds and, driving out towards Warley, the Thatchers? Arms plus a few old hotels.
Proximity to London ? You can be on the right side of London for the financial centres (London, EC1, EC2, EC3, EC4 and E14) and for Kent and Sussex ? English Heritage sites including castles, are just over the Dartford Bridge, this alone would make Upminster the choice for me or perhaps I am blinded by fondness for the place!
Trips to France are also easy on the Eurostar, park at Ebbsfleet and bag an early seat.
Teenagers will probably thank you for deciding to live under 20minutes from Hoxton, Spitalfields and Shoreditch ? staying out late means that night buses, trains and taxis are a much easier option back to Upminster.
It even has some street cred - was Ian Dury?s old stomping ground, he even named an album after it.