It really depends on what
you like the look of
My favourites are by Essex Miniatures, but a good proportion of my armies are from Essex. Some aren't so fond of them.
I have some Vikings by Baueda along with some Two Dragon Miniatures that are quite nice, but I did find the Two Dragons Vikings a little on the short side.
I also have some Vikings from Donnington Miniatures. These are from their New-Era range -
http://shop.ancient-modern.co.uk/vikings-126-c.aspThese are also nice, however they are little larger than most of my 15mm miniatures (Essex).
I don't own any Splintered Light's Vikings, but the other historical ranges I do have miniatures from are great.
Khurasan Miniatures also has a range of Vikings, but I don't own any.