I haven't bought anything from Musician's Friend yet, but do have an account and cc card with them. And I have cards with Sweetwater and GC too.
Now I have made two major purchases with Sweetwater. The first was an Ibanez SR400EQM and GK MB210-II. It was a big hassle and I ended up getting a new service rep over it. The good out of that purchase was it was at my door in two days and not the 5 like I was quoted. And the new service rep I got out of it does a great job at customer service. Every now and then he will call and talk shop, not often though. And every now and then he will email me just to check in, which is fine too. But I don't get bombarded. And the rep he replaced I couldn't ever get an answer out of when I was trying to spend my money.
My 2nd purchase with SW was around $360, completely handled by my new rep, and you would have thought I was their best customer.
Then there's GC, I have one local so I buy at the store instead of online. I'm friends with one of the managers, and one of their guitar instructors. They actually have a guitar tech who knows what he's doing as well. But... There is one salesperson / manager that I have had to deal with on occasion and he's been kind of snobby, even when I was doing what would have been a $700 sale. He actually handed it off to another salesperson. So with that I called Sweetwater standing right there in front of them and said see ya, I'm going home to order this stuff online. I walked out of GC for $518 and extremely happy. Then I was in there the other day, I only spent 45 bucks, and this same manager treated me really well for the first time. Maybe's he's turning a corner or finally got him a girlfriend. I don't know.
I really wish my local guitar shop could do more for me. But they don't handle a lot of bass stuff. But the owner is there 4 days a week. And he's the type that if you need something and it's not available anywhere locally, he'll get on the phone and order it. I recently needed a set of short scale D'Addario Chrome flats. They're not even in the D'Addario catalog the guitar store had for ordering. So the owner got on the phone to D'Addario, placed his weekly string order early so he could piggyback mine on the shipping so it didn't cost me extra. I had them within hours of a gig I really wanted them for two days later. And he always thanks me for my business. I hope to do some bigger, major purchases with them in the future. But they have to have the gear I want or need. I will say this, they have been a good source for used pedals. And I got my eye on a rig he just took in on consignment.
All I can say is people are funny. If they don't own the business they are less likely to care if they're having a bad day or whatever affects you as a customer.