Not going to argue Wales would be better equipped but a fully fit v fully fit the bookies would favour England and they'd likely be right given the form record of both and home advantage.
The Lions series though you'll see many people argue that Gatland's/Howley's loyalty to some Welsh players and tactics probably hampered a potential series win, even then they couldn't beat a side depleted to 14 men for the majority of a match.
Part of me is utterly baffled that some people still underestimate England after the past two years, except for NZ (and possibly even then) they'll go into any game at Twickenham as favourites. They'll even go into most away matches as favourites as well with only Ireland and NZ considered as likely losses.