Changing the electrolytic capacitors in vintage tube gear is a must
these days, but no one makes the old style (large size) caps anymore.
I personally do not trust these small modern caps to last very long.
Many computer motherboards have proven how short the life span is on
modern caps, and most of them are low voltage types.

Those old caps have lasted 40, 50 sometimes 60 years. I doubt any modern
caps will last even 10 years. I tend to wonder if that is because of
their small size. Or is it just the construction or materials used?
There are some NOS (new old stock) caps available, but they fail
regardless if they were used or not, since the electrolyte drys out and
moisture may enter them as well.

I dont mind changing caps on vintage gear once, but if I have to change
them every 5 or 10 years, I will not be happy.

But since new caps are no longer made, which are made the same as the
old ones they are replacing, I have little choice but to use these small
modern ones.

That leads to finding brands which are reliable. And I assume price
tells all. Cheap imports are likely the worst, while high priced US made
ones will last longer.

I doubt any modern caps will last even close to the life span of the old
ones, but which brands are the best? (Particularly the ones used for
high voltages in tube gear).