Mole Catcher might be too dark and 'hoppy' for some people's taste. Also, if your father likes supping several pints at a time, it's rather strong and what I'd regard as a 'hangover beer'.
Moles Tap is a what drinkers refer to as a 'session beer', but the Fuggles hops predominantly used in it don't (in my opinion) give as much flavour as you get from a beer which also uses Goldings hops.
Moles Best Bitter has (through the use of Goldings hops) more of a flavour which will remain in the mouth for longer. At 4% ABV it's also not too strong.
I'd regard Landlord's Choice as the 'special occasion' variation of Moles Best Bitter. (It should have a more marked flavour, which will stay in the mouth for longer. At 4.5% ABV it's 'strongish' but not 'knockout')
I'd put Landlord's Choice at the top of your list, with Moles Best Bitter not far behind.
Chris