The answer is simple: any - or all of them! The latter is my attitude right there - also documented in all the photos below. From my experience ficus plants are incredibly grateful and fast-growing. They are very difficult to over-water or to dry out (touch wood!) but one watering a week is plenty. They are happy on sunny window sills (but strong bright sun can scorch their leaves - not that we have that much of it here in the UK) but will also be quite content in half shade. As to the varieties, these are my favourites:
FICUS LYRATA: Perhaps the most famous houseplant - somewhere I've read that Ficus Lyrata (also known as the Fiddle Leaf Fig) has been named the houseplant of the decade (a bloody decade!!). It grows really quickly and has huge leaves. I'm sure you've spotted this one on Pinterest!
FICUS BENJAMINA: Probably the most common old school ficus houseplant variety - also called the Weeping Fig. Its leaves are small and kinda sad looking - some of the varieties have really thick leaves and when you shake them they chime!
FICUS ELASTICA: The Rubber Fig is my personal favourite - it comes in a number of different colour variations and its leaves are ridiculously thick (hence the name, Tereza, doh!).
FICUS MICROCARPA: The first fig tree I've ever bought (the moclame variety from IKEA - they have a decent selection, just sayin'). They are also called the Curtain or the Laurel Figs. It's also the first fig I've ever grown from cuttings - such a rewarding process - you can read full post here.
FICUS PUMILA: The most recent addition to my fig tree family - the Creeping Fig. This one looks nothing like a fig tree and because of its vines you can have it in a hanging basket!
You can buy ficus plants in most garden centres, although some varieties are a little harder to come by. A good range is available in IKEA (click here) and for locals from the West Midlands area - the Hollybush Garden Centre (click here). If you can't find the variety you're looking for then try E-Bay!
What's your favourite houseplant?