I can highly recommend KBIS i've been with them years. I wouldn't recommend E&L. Wherever you go make sure you get the best cover possible. Read the small print! I was caught out on vets fees once and when my horse ended up going to the vets with a fracture cheek he was not covered for livery at the vets. It was in the tiny tiny tiny print so make sure you have everything you need!
Second vote for KBIS been with them many years and the one major claim one the death of my filly from grass sickness was settled in days. Very helpful and sympathetic when you need them.
NFU and Petplan. There is one you should avoid at all costs but I dont think I can name them on here, especially as almost every week their bloody waste of paper leaflet falls out of my horse and hound!!! p.m me if you need to know!!! (not that I'd know how to read a p.m!!- I'm not very techy!!)