Have done both for the past couple of years. Both are great. BD is bigger and i'd say a little bit more diverse musically. They tend to book acts from across the years too, and there are some real gems this year. Last year James and Leftfield were brilliant, but Gentlemans Dub club and Afroceltic Sound system where top. No sponsorship anywhere, which tells you its a festival run by people who love festivals (Levellers obviously)
EoR is more indie. With the exception of a couple they're all new to me this year. EoR has probably the best food I've ever seen at a festival too, plus there's a really good late night area with lots of effort going into the site. Savages where off the scale in terms of a performance. Comedy was top class too, although this year they had some rubbish queuing system that really spoilt it. Lots of complains so hopefully they wont repeat that.
Both are set in beautiful parts of the West Country.
If I had to choose I'd probably go BD, but I don't so am doing both again!