St Albans is pretty good for commuting from that way (fast frequent trains, some direct to Farringdon in about 25 mins) – not that cheap though. Can head straight out to countryside but probably better for road than MTB rides. If you must commute, try to avoid any train/tube interchange – more points of failure, more time spent, more misery.
Generally, I agree with TheBrick's post though. Better to have an hour's drive to good riding on the weekend than spend an hour an each way on a packed commuter train every single working day. If you cycle commute, there are quite a few nice, central areas that are good value because they're not within 15 mins walk of a tube station.
This generally applies more if you're young, free and single though. If you have kids, you inevitably want more space for your money and once they hit 5 then factors like local schools become more important.