IMO Preiser make some of the best figures available. Some of their poses and details are pretty much unbeatable. The downside is that they are becoming ridiculously over-priced, often well over £10 per figure. However, bargains are available if you are patient. I recently got a very nice set of 3 passengers for £5 because they had been wrongly listed on ebay. Their full RRP is around £35!! Also Preiser's choice of model often seems pretty ridiculous. Quite why they spend so much time and effort on such things as vampires, popes (!!!!) and men in mankinis is beyond me - takes all sorts I suppose?
They also make some pretty silly errors (engaging rivet counter mode). Modelling a pair of golfers is a pretty sound idea, but surely they shouldn't BOTH be taking a shot? Wouldn't it be better if one of them was leaning on his/her club either admiring their partner's shot - or laughing at it if my golfing experiences are anything to go by.
I'm also a fan of Model Citizens, but as mentioned in another thread, they seem hard to come by in the UK these days.
IMO the best compromise are the Bachmann Scenecraft range. Some of these are every bit as good as Preiser, but for much less than half the price. The downside is that they seem to be made from some sort of resin rather than plastic and often become brittle when they've been outside for a while, in fact if you drop them they often shatter. The standard of painting and realism of poses can also be a bit variable.
There are also a few smaller producers around such as George Turner. Some of his figures are pretty good, although to my eyes many of them have legs which are too small in proportion to their bodies. If you can hide this though, they can look great. In fact the driver of my pannier tank is one of my all time favourites.
I'm afraid that using Playmobil people is not for me and I cannot for the life of me understand why Busybodies seem to have completely dominated in the live steam fraternity. To see a fantastically detailed live steam loco (with the correct number of rivets) with a couple of these "cartoon characters" looking out of the cab - it just gives me an emperor's new clothes moment. Once again, takes all sorts.

