Thats a lot of miles on front tyres. Was it mostly motorway.? Did you rotate front to rear to equalise wear over all four ?
I too recommend fitting all seasons. They can have surprisingly long wear. But its not recommended fitting 2 all seasons and 2 summer. But then again even when all 4 tyres are either summer or all season its not recommended having a different brand of tyre, or significantly different tread depth between front and rear or on the same axle.
For many years I always put my 'best' tyres on the front (with front wheel drive) but apparently experts recommend putting them on the rear, as front wheels breaking away due to reduced tread grip is easier to control than rear wheels. So whichever type ,if you only buy 2 they should be put on the rear, unless the rears still have similar tread depth. On the plus side if you put the older ones on the front they will wear quicker than the new ones on the rear, so when the front two are due for replacement tread wear will now be similar front and rear.