A little rant. Passive Guitars and Basses love the Hi Impedance of a good DI. The Countryman is 11 Million Ohms. Nearly all DI's have a simple parallel in and out. So.... if you connect a tuner in line or to the output socket it shunts the load down to say 50K. A disaster sound -wise.
The old Boss DB1 offers an unbalanced buffered output. This is an excellent addition. However inserting the 20 or 40 dB pad again shunts the input impedance, again ruining the sound.
My perfect DI should have:-
Hi-Z input 10M or so.
A pad that does not change the input Z.
An optional or extra buffered output to drive tuners, pedals etc.
A top grade transformer output.
Strangely I have not found any such product.
In answer to the original question, here are my favourites.
EMO passive. Excellent transformer, sweet sound.
Countryman FET 85. Active, bulletproof, impeccable sound, a little punchy.
Boss DB1. Maybe obsolete. Neutral, no sound, unbalanced output option.
BSS AR133, the newer green ones are superb. The old grey ones were awful.
I am reliably informed that the LittleLabs IBP is a great active DI.
The Behringer active DI crops up everywhere. It is the single worst sounding piece of equipment I have ever come across.
Best Regards, DD SoundSound - Homepage