Tube preamplifier tube choice help please

I would like to ask which tube is better linearity and sound among 6SN7 and 6NP1 tubes in preamplification or what are their pros and cons
There are two brands tube preamplifiers I intend to buy they have almost same topology, one uses only a pair 6SN7(Tungsol) and the other one uses only a pair 6NP1 (Russian) they both have
tube rectifiers and roughly same prices
I have not used those tubes in any application before so I would like to hear your comments please.
Thanks in advance
there are at least a few vintage tube dealers on the net with extensive documentation on their sites regarding the different versions of tubes - especially 6SN7s.
You will have significantly more tube rolling flexibility with the 6SN7 preamp. This is an advantage, IMO.
A lot of audio equipment manufacturers utilize the 6SN7 and millions of these tubes were manufactured for the military, so there is a good supply and more choices for tube rolling. My favorite 6SN7s are Slyvania for accuracy
For tubey sound I like RCA and Tungsol for smoothness
Agon Member JSAUTTER is a very knowledgeable source for tubes
Brent Jesse is a good dealer on the web. I have no comment or opinion on the 6np1
I have Cary SLP 98.

I tried few 6sn7 tubes in the front and always have sylvania gtb at the back.I tried tungsol brown base,sylvania brown base and few more and sound really good..Then I tried these 6sn7 tubes from russsia with a 1578 stamp on the glass ...then I stop looking for more 6sn7 and always happy listening to music now.I recommend these tubes to all A'gon member who own a Cary Slp-98 pre-amp and what a difference.Please try it!!Don't ask me now how it sound but i do believed you will be happy with this tube especially mate with cary slp-98.
The 6SN7 is one of the best preamp tubes.Plus you could do tube rolling.♫
The 6sn7 will probably be easier to sell as a used item
the russian 1578 tubes, if genuine, are exceptional. i use them for input and sylvania bad boys for output on my wyetech opal pre, after much experimenting, and it is a great combo. ken-rads add more warmth if you like that. 6sn7's are widely available and offer many tube-rolling opportunities to get the sound you want.