The really deep searchers, and the winner is ...

[User923005]

select sum(acd * 1.0) / count(acd) as avedepth, Engine from ccrl4040 group by Engine order by avedepth

{big snip}
27.007593 Quazar 0.3b 32-bit
27.202154 Stockfish 2.3.1 64-bit
27.242826 Chiron 1.5 64-bit
27.288728 Stockfish 1.9.1 64-bit
27.398481 Tornado 4.3 64-bit
27.677473 Stockfish 2.0.1 64-bit
27.950293 Sting SF 2 64-bit 4CPU
27.999314 Chiron 1.1a 64-bit
28.015768 Stockfish 2.1.1 64-bit
28.077289 Sting SF 4 64-bit 4CPU
28.339449 Hannibal 1.4b 64-bit 4CPU
28.345462 Stockfish 4 64-bit
28.416001 Chiron 1.1a 64-bit 4CPU
28.629037 Stockfish 3 64-bit
28.629988 Stockfish 2.2.2 64-bit
28.756338 Tornado 4.88 64-bit 4CPU
28.986880 Sting SF 3 64-bit 4CPU
29.099846 Bobcat 2.75 64-bit
29.439966 Chiron 1.5 64-bit 4CPU
29.461985 Bobcat 20110414 64-bit
29.677147 Stockfish DD 64-bit
29.878004 EXchess 7.11b 64-bit
30.149394 Chiron 2 64-bit
30.162665 EXchess 7.03b 64-bit
30.214248 Stockfish 2.2.2 64-bit 4CPU
30.517295 Chiron 2 64-bit 4CPU
30.585931 EXchess 6.71b 64-bit
30.674069 Stockfish 2.3.1 64-bit 4CPU
31.102020 EXchess 7.18b 64-bit
31.314309 EXchess 6.50b 64-bit
31.653003 Stockfish 3 64-bit 4CPU
33.009019 Stockfish 4 64-bit 4CPU
34.657770 Stockfish DD 64-bit 4CPU
35.022158 EXchess 7.18b 64-bit 4CPU

Exchess 7.18b searches more deeply than any other engine -- even Stockfish.
Sure surprised me.