I really like the 5814 tube type period. It was made for the military and is made to mil specs. It does have a higher filament current draw than a 12au7 or 6189. I have a Sylvania Gold Brand 5814 that is very nice and smooth with awesome detail. The GB is (was) a higher quality version with gold pins (typically). But the real winner in this tube for Sylvania are the the "black plate" versions. If you can find a balanced one of those for less than $20, you've done very well. RCA black plates are great, too. The best ones date back into the 1950s. I have several that are one year younger than I am... from 1956.
Look around... they are out there and they can be had cheaply. The 5814 and 6189 are both variants of the 12au7. You can't go too far wrong with either.