Trank - a highly talented director whose Chronicle is one of the better superhero films of the recent explosion of the things - turned out a film that was obviously tampered with but also suffered from severe miscasting. The result was panned by critics and did poorly at the box office; Marvel however sealed the deal by doing every little thing they could to undermine it - while Fox owned the film rights Marvel owned basically everything else and were effectively able to block any F4 merchandise at the time of the film to avoid it competing with stuff they owned 100%. This even led to the long-running comic book series being placed on hiatus while Lego were obviously leant on to make sure no F4 characters appeared in their ongoing Marvel Superheroes line.
As ever where there's such a gap in the market there are Chinese bootleggers. Copies of Lego's superhero minifigures are abundant and great fun; most are near-perfect copies of those available in sets, usually for around £2 a piece. But if you're a bootlegger with access to moulds and tampographing equipment it's probably easy enough to design your own and the gap in the market for F4 toys gave several (naturally elusive, considering the copyright violation) companies inspiration. There have been sets of both the classic costumes and the white ones seen in the film; after a little trial and error I've managed to put together a set that I like - or two sets, as there are options out there to do a 'casual' and 'action' set.
There are two or three Reeds out there; a stretched version with elongated legs and arms, both lifted from the licenced Minifigure of Woody from Toy Story, is the most common and is available in both the blue classic and white uniforms. It's actually a decent enough way of representing his power in hard plastic while also meaning you can actually do stuff with him. There's a neat version of the swept-back hair complete with greying temples that really adds to the personality as well.
The only 'standard' Minifigure I've yet come across for Reed is an underwhelming little thing with a silly face design and a much less impressive hairpiece (though it does still have grey on the temples). Really, the most sensible option was to buy a second 'stretched' figure and swap in standard sized arms and legs, which were easy enough to find. Accessories-wise I think the gun came with the stretched version and I have no idea where the other little bit of machinery the smaller one is holding is from; the fun thing is that with 30+ years of space-themed Lego there are lots of fun bits of kit that go nicely as one of Reed's gadgets.
THE INVISIBLE WOMAN
There are again two or three versions of Sue, though these are closer and more consistent that the different Reeds. Again, there's blue, white and powered up. The latter is one of my favourite Minifigs outright; there's something very, very cool about the transparent plastic all over while the little detail paint apps really pop out even if they're slightly illogical. The uniform seems to correlate more with the white version but not by enough to bother me and as you can gather I'm pretty particular about this sort of thing. Perhaps as a reflection of how cool it is this is one of the slightly harder to find off-brand figures, but not to the point where you'll spend a fortune.
The 'standard' version is available in blue or white. The blue version is more refined than the similar Reed and complements the 'invisible' version nicely, with the same hair and facial features, though the uniform doesn't quite line up. And the fun thing is that if you want a representation of Sue's forcefield power basically any shaped clear part that can clip to the Minifigure's hand will do.
THE HUMAN TORCH
There have been several versions of Johnny in both flame on and standard. For the 'action' one there are three 'classic' versions - a solid version with dark red plastic, a transparent version and a transparent version with the '4' logo. The second is the more accurate no doubt but I eventually settled on the latter for the entirely selfish reason that it means the one without the logo can be repurposed as the original Human Torch. More obscure is a version based on the most recent live action movie where the character was played by Michael B Jordan; as a result the Minifigure head was brown (even through Jordan's skin colour can't be seen when he's flaming) and the uniform and wavy flame hair are yellow; this is often labelled as Pyro due to its' broad similarities to the Brotherhood member but it's got a 4 logo. Very odd.
For standard versions there is again the white and blue. The latter again fits well, though I can never quite decide on a hairpiece that looks good; the blonde spiky one fits the character's personality in lieu of anything much better; the modern side-parting might be a better fit but isn't yet out in any 'fair' colours.
The Thing has had probably the most diverse treatment, with three totally different Big Figs and at least one Minifigure out. The former takes three different approaches - one seems to be a heavy retool of the official Hulk Big Fig and is by far the best fit; for added variety this is available in blue, white or red (either a reference to the team briefly having red uniforms or I have half a recollection of him donning these when he briefly left) pants. There's also a brown figure that's a notably different sculpt featuring a large cylindrical Minifigure-style ehad; the style doesn't really work even if the colours and detailing are nicer that the orange one. Finally there's a totally different sculpt with seems based on the latest film and looks awful.
Personally I'm always torn on Big Figs; they feel like cheating but they do the job well and some characters just don't look right at a small scale. The Thing is arguably one, though I picked up the small Minifigure as much to line up with the other three 'standard' guys. It's got some nice detailing but does look underwhelming at the same height (though it's worth nothing the Thing was illustrated as roughly human style in the first two films).