I prefer F&T over other brands of cap used in valve amps, as they have the best specifications in therms of lifetime.
One feature of electrolytic caps not often discussed is temperature rating.
Your capacitor datasheet will (well should) give a life expectancy at maximum temperature rating and maximum ripple current, with curves to show the effects of running the caps below both these parameters.
For every 10degC you below its rated temperature you run a cap, you double its life. So a 105degC/1000h cap will last four times as long as an 85deg/1000h rated cap).
Most caps are rated at 85deg.
I don't use JJ caps. JJ caps are rated for 1000h at 70degC, which seems on the low side to me. Furthermore their can caps are slightly bigger than the standard 32mm can found in vintage amps, so are harder to retro fit when repairing older amps.
I don't Sprague Atoms. Some Sprague Atoms are only rated at 65degC. Indeed I saw some of these today in an amp. After much badgering I managed to extract a (fairly derisory to say the least) datasheet from Vishay for the Sprague Atoms, and I was not impressed. They are also expensive
Ask Jan First stock most of the F&T range.
http://www.askjanfirst.de/eindex.htmIf you don't mind using radial caps, there is an excellent selection of inexpensive 105degC rated caps up to 450 VDC, eg the Panasonic EE series, rated for 10,000 hours at 105degC
http://uk.farnell.com/panasonic/eeuee2w470/capacitor-47uf-450v-16x31-5mm/dp/1673505
