Buy 12ax7 tube

I wold take the Raytheon or RCA over the Russian Genalex. I don't know where you'll get any of them for $40 though. I use Telefunken medical grade AX7 in my phono stage and original Tesla ECC803S for the AX7's in my amp. Telefunken is generally recognized as the most accurate and tonally neutral 12AX7 ever made. 

The Genelax 12AX7 tubes worked wonders in my McIntosh C2500 preamp. Much more fully fleshed sound.  

Apart from the primary consideration that must be made, i.e. any tube's potential to synergize with your other components, speakers, room acoustics, etc, assuming you want a neutal tube, ala the Telefunken, which I consider one of the best, you might consider the not so old NOS EI12ax7a which was made with the Telefunken machinery which was purchased by EI. I just saw someone selling an unused octet of these tubes  (labeled ARC) for slightly under $200. A deal(!) if you can justify getting the octet. If you are interested in the Tele's you might do some research first. I haven't heard the other tubes you mentioned so I can't compare. 

I found these tube for 40$ in taobao
I cant afford more expensive stuff than 40$