Sort of depends on what's more important to you, the higher level of service or the view? It's my understanding that the BC concierge rooms are slightly larger than a standard room. Hopefully someone who's stayed in both can confirm or deny this. Chip is correct that they are all on the 5th floor, which also houses the on site concierge staff and the lounge. An elevator key card (specially coded room key card) is necessary to access this floor.
With concierge service, you will have the benefit of a pre-planning team to make all your dining, recreation, tour, tickets, etc. needs. IMO, the group that services the Epcot resorts are really the best. Very friendly, warm and extremely helpful. Upon arrival, you just need to slide the key card that the pre-planning team sends you into the slot on the elevator and ride up to the 5th floor for a private check-in. Concierge CM's are available daily from 7am-10pm to check guests in and assist them with any last minute plans or changes. There's a small but cozy lounge available which has a nice continental breakfast each morning, cold drinks available throughout the day and various other snacks and goodies at specific times. In the evening, wine and beer are available and late night desserts and cordials are served from 8-10pm. Other than breakfast, it's not anything that could be considered a meal replacement, but it's great for a quick bite to hold tummies over.
Good luck with your decision.
Tammi