Sounds like you really can't go wrong with any of those choices. I've stayed at all these resorts outside of the Swan Reserve. I've stayed at the S/D a bunch and for us, it's a great property with deluxe amenities for moderate pricing.
Few items to note- location wise, Swan/Dolphin and SR are all very convenient to Epcot and DHS with SR being a little further from Epcot than S/D but a tad bit closer to DHS. Keep in mind, the Dolphin hotel is much larger than the Swan as far as layout and has hallways that seem to go on forever. We last stayed at the Dolphin in April and I had remembered how long those hallways can feel after 20K steps. Swan Reserve is likely much smaller than both S/D (have not stayed at SR). Also, the Dolphin does not have Queen beds which could be a deal killer. The Swan does, but you get double beds at Dolphin. Of these two resorts, we definitely prefer Swan over Dolphin for the larger beds and not as large of a resort feel. Other items to note when staying at S/D and SR-
- All these resorts share buses which is not a big deal but you should be heads up on this. The resorts are so close it's really not a big inconvenience since it's just one stop at each entrance.
- These buses can go to all disney park entrances except for MK. You will be dropped off and picked up at the TTC. Also not a deal breaker but something you should be aware of for your park planning as you need to build in some time.
- Can't catch a minnie van from these resorts, only regular ride share.
- You get the same disney deluxe resort benefits at all three of these resorts so you'll get access to ETPE and EEH.
- All of these resorts share laundry facilities and in room dining- believe the laundry room is at the dolphin
- S/D guests share the main grotto pool however S/D guests can't use the SR pool BUT SR guests can use any pools at any of the three hotels. And SR guests also have access to any health facilities at all 3 resorts. Also not a big deal but things to note
- S/D and I'm sure SR but not sure about reserve's fees, all charge a resort fee and also charge for parking. Of course these fees also have taxes, so be sure to factor that in for your stay. S/D Resort fee is $35/nt and parking is $32/nt. These end up being about $40/nt and $34/nt with taxes included so be sure to factor that into your cost analysis.
Beach Club-has a really great pool and something to consider if you have kids or kids of an age that would swim. Could also be a negative if you prefer a quieter more relaxing pool experience. BC is also closer to Epcot but is the furthest from DHS. And as you mentioned, you can have room charging privileges with your MB, which you won't have at SR or Swan.
Swan - this is our favorite non-disney resort for the location, amenities, value and overall accommodations. Definitely takes a little longer to get to Epcot than BC but it's still a great location. Staying at Swan adds about 5 min to our walks but we usually end up catching a boat to the parks throughout our stay. We find the buses here pretty reasonably timed. We've had a few longer waits but nothing any other disney resort wouldn't have. The other intangible negative that my kids remind of is that it's not disney themed so while it's on disney property, it can make you feel outside of the bubble. I don't get that feeling but I understand it.
Swan Reserve (+0.7k) - 1BR Signature Suite- have not stayed here. Sorry
Without knowing which parks you'll frequent the most and how much you'll be at your resort/in your room, I can't really judge what might be the best fit. But, if it's a typical trip for us with hitting all 4 parks at least once, usually taking midday breaks, park hopping or just sleeping in, I'd pick Swan for the cost saves. I don't see a point in booking a large suite when the space may not be needed. And for us, we usually end up at S/D over Boardwalk and BC simply because we can't justify the price for such similar accommodations. MB charging is not such a big deal for us so that's not enough to keep me paying higher prices.