best preamps

MY ’Best Preamp" is the one I ended up getting for free. I ran into a used Audio Research SP-10 locally at a dealer, for $800, of which I traded useless junk to lower the price to my $600 cash. Within a few weeks after, I bought a used Audio Research SP-15 off the goN’ for $1500. So I had both at the same time. The SP-15 crushed the SP-10 sound wise. No question. (though if the SP-10 had the best tubes ever, it might have changed the balance. The SP-10 uses like 11 tubes.)
So the typical SP-10 price on Audiogon was $3K. I listed my SP-10 for $2300 (notice $1500 and $800 equal $2300) and said buy some good tubes. Amazing I posted the ad at 7AM, and in half an hour had five offers to buy. (I should have asked for more money? Anyway, the SP-10 sold. And I basically got the Sp-15 for free.
Free is good. Best deal I ever did. So that is why the Audio Research SP-15 is the BEST PREAMP in my opinion.

Sorry, but I don't think your question is a good one. There is no "best." If there was, all of us would own the same brand of preamp!

The latest McIntosh C52 is a sleeper. Remember you have to use the included equalizer  to compare with other more ´´ tiped up ’´ preamps out there. Makes a good match with brighter speakers like Focal or Magico.

@jhamond987 

When you said unlimited budget, how far do you want to go? Are you looking to get just the linestage preamp or the entire setup and system? What are your current setup and system? Did you already have a setup or trying to start from scratch? 
Without knowing the rest of your gears, If you already have a setup, it's hard to make recommendations. 

I love my McIntosh C2200! Used under $3500.