Best EL34G tubes for Cary Audio cad 40M?

Right now they have Sovtek EL34G, but it is time to change.
I would like to know what to buy for upgrading and what is the optimal one? Hope someone cane help me!
I have the same amp. I've had Chinese tubes, my least favorite--don't even remember which brand they were. I've had the Sovtek's and really liked them, but had some reliability problems with them. I've had the Svetlana's, they were too soft. I'm now using Electro Harmonix, which thus far have been my favorites--very similar to the Sovteks (they may even come from the same manufacturing facility). I have been tempted to go NOS, on my phone pre-amp that made a huge difference. I did go NOS on the input tubes (RCA brown base). Tesla and Siemens are two of the EL34s I have not tried, but would like to. Perhaps others can comment on these tubes.
I own all of the tubes being discussed, as well as the Siemens / Telefunken AEG. The Teslas I recently bought are the blue glass version, a nice alternative to the clear (same performance). I would rate all that I own in the following order, from most to least favorite:

Mullard dual getter, welded plate EL34. Mullard single getter, welded plate EL34. Amperex double getter, welded plate EL34. Amperex single getter, welded plate EL34. Same brands as two previous, without welded plates. Siemens /or Telefunken AEG EL34. Tesla E34L (all colors of glass). Electro Harmonix EL34. Sovtek EL34. Svetlana EL34. Chinese EL34.

This list does not take into consideration old EL34 tubes that may have been constructed around the same time as the vintage Mullard and Amperex. It may safely be stated that the older the tube is, the better the quality and sound, provided they are not completely worn out.

I recently purchased some old EL34 tubes marked Dynaco. These were manufactured by Mullard for the Dynaco Stereo 70 amps of the early 1960's. The silver was almost completely gone from the inside, and the base had been scraped with a knife to remove a previously applied sticker. The plate showed signs of having gotten too hot (scorch marks), and most of the logos are missing. After all this time and abuse, it still out performs every current production tube I own.
I have used the Sovtek, JJ Teslas and Valve Arts in my Copland CTA-402 integrated. My favorites are the Valve Arts. Abstract7 mentions the Harmonix. Here is a link to a dutch auction for a MQ at $49.99. These retail at $71.00 on Harmonix web page.
Here's the link to the Valve Arts.
There are a bunch of EL34s for auction on singles, MPs and MQs on Ebay all the time. Sometimes they are a good deal, sometime they are overbid.
This was discussed recently and nothings changed. I totally agree with AP, save for the order. 1-Amperex double D getter 2-Mullard fat base double getter 3-Mullard reg. base double getter 4-Mullard single getter. All of this is system dependent, but all put all others mentioned to shame. When you factor in that the NOS will last at least twice as long, the cost becomes more palatable.