I should add, the Fenris, and TAG ones are a good fit, IMHO - the only difference is the length of the wheelbase, and given the different varieties of humvee (and the fact that the Fenris one I measured was the pickup version) I think they are spot on.
The Imprint ones are nice - i've got their Bradley & T-90 for my Battlefield project, but already have plenty of TAG/Fenris Humvees, and so will stick with them, for that particular model.
The FOA ones, are, again, nice models, but just that bit smaller than the others - good models, in themselves, but I wouldn't mix them with the larger Imprint ones.
Hope this helps.