It is so interesting to see how different tubes sound different in different systems. I have a pair of EF95 Amperex tubes made in England which look exactly like Mullards, but they don't work for me. However, the Mullards I have sound much better. (Don't fall into the trap of Australian made Mullard look alikes that don't sound nearly as good - the letters SDA appear on these.)
The Amperex 6AK5/5654 tubes made in Holland are much harder to find, but sound very different and have a very strong bass.
Bottom line: You have to find the tubes that sound the best on your equipment using your own judgement. Don't know why you have such problems with microphonics - maybe you could experiment with a different placement of your amp, or maybe move something that may cause the microphonic coupling.
In the past I have seen the LM Ericsson tubes on EBay for around $20/pair including shipping (did not sell then). Did not bite because I will not spend more than $8/tube, and preferably less than that amount for a pair.
Found an Ebay listing from June last year that tells the story: Be patient and you will find the right price - sorry I missed it, but I was not looking then. (Hint: look for 5591 as well.)