So damn hard deciding which tube preamp to buy!

Conrad-Johnson's GAT Preamp is a reference for many reviewers.  You should be able to hear it locally and find a discount as well.

Just narrow it down to a couple of prospects then research the hell out of them. Find out which dealer offers a 30 day trial with money back guarantee. We all been through it before. On the other hand it used to be easy to turn over used gear on Audiogon, not so easily done any more.

So you have $10 to $25k

[sorry for my English]
...and you are asking what to do?Very simple, you buy (blindly) the very best preamplifier of the world that money can buy in that price range: Aries Cerat Incito S (approx. $15.000).
I don' like tubes (honey-topping on everything), but this one is totally different. SET tube design, with zero feed-back, and transistor-like figures. Watch out, 5 chokes and 75lb (!!!). Romote control, with relays (no potentiometer, they all suck).
 It replaced favorably a Cello Encore (in an acquaintance's system), and even caught back to active preamp afficionados of passive preamps.

That thing is not of this world, really. Well beyond ALL the big names of high-end.

If you have $25,000  to spend for a tube preamp.You should have no problem picking one out...even if you buy something you don't like just have you chauffeur return it.

Well it isn't actually that hard. Just pick one of these:
https://www.vinylsavor.com/en/products/line/

It will be built to order just for you. You can specify what and how many inputs and outputs, chassis style, finish, choice of wood. Thomas even makes his own world class DHT tubes. Who else does that?