Bit early but I was looking at the 6 probable teams leaving the Championship against the 6 that could replace them I'd say next season's league will be tougher
Out going:
Burnley
Sheffield United
Middlesbrough
Wigan
Huddersfield
Blackpool
Incoming :
Southampton
Everton
Bournemouth
Sheffield Wednesday
Plymouth
Ipswich
Could be a very tough league next year. Lot of huge teams added along yoyo club Bournemouth.
You missed Coventry from the list.
Teams coming down from the Prem are always strong, parachute payments and all that - don't think it really matters who they are. Although a big club that's not used to the Championship, and absolutely capitulates with the fans all over their backs, would definitely be preferable.