My current favourite combination is EF86 drivers and GEC 6as7g power tubes. GEC 6as7g is very rare and hard to obtain, but the TungSol 6080 and Tung Sol 6as7g get 95% of the way there for a fraction of the price when they do show up for sale. If you're willing to try, 4x GEC A2293/CV4079 with adapters off ebay get even closer to the GEC 6as7g sound, obtainable for under 100$.
Tung sol 5998 comes up often but quite expensive as well. About as detailed and wide sounding as the above. If you prefer a slightly warmer/more mellow sound try changing the driver tubes out for RCA 5963 red hots (cheap and abundant) or tung sol 6sj7gt mesh plates (hard to find).
Other great power tubes with a warmer sound are bendix 6080 (check for graphite plates, these are very rare though), mullard 6080, or sylvania 6080. RCA 6as7g is abundant and cheap, and sound great.