My usual go-to for "tracking" is the Studer at 15ips. Occasionally on synths or some electric guitars I'll load up an Akai or Teac (the cassette).
For master buss I almost always use the Revox ATR (0); I just love the sound of that program for the master buss. I don't get around to using the Revox for much else. Occasionally the Studer at 30ips is more appropriate than the Revox/ATR.
For vintage-y sounding stuff, I use the Wollensak. The thing about the Wol is that each pass is crazy different from each other pass. Choosing between the 7 FullBand programs and the (I think it is) 150-tape programs is a track by track decision. I also use these Wol programs for a wide variety of effect-ish choices.
Interestingly I was at my grandfather's helping him clean out an old closet last week and he actually has one of those Wollensak/Scotch units (I think it's the same model Michael sampled), I think if I help him digitize his library I might be able to talk him into handing it over. Not sure if I'm up to the task (certainly not as qualified as Michael) of sampling some more tapes on this monster but it's something I'm definitely interested in, I get a lot of use out of this machine.
The Studer -15db @ 30 ips is great for the master bus and the 15 ips program @ -10 db is great for individual sounds too.
Maybe its -10 for the 30 ips, and -15 for the 15 ips program, always get em' confused but these generally are my go to 'nicerizer' type things.
Don't discredit the OTR programs either. Sometimes those work better than the Studer programs for individual sources and or master bus duties. OTR @ 30 ips can have a nice lift and 'sheen' to the sound, but with a little bit of movement of energy away from the low end (sometimes this can be good or bad, it all depends).
The Akai and Sony programs are fantastic on anything from softening/darkening certain drum loops, guitars, synths, really whatever works.
I like using these programs too for tonal and harmonic shifting for really getting sounds their own vibe but still retain a cohesive flavor for the mix. Michael gave me this great advice.
It takes A LOT of time to not only learn what each program can do, but the time on trying each tape for each sound.
Sometimes using the 'track to a Studer' and then using the other programs to tonally shape things is really awesome too.
It's too smeary for me and makes a Hi-end bump which I mostly don't like the character of. It's not particularly bad, it's rather that the Otari does the things I'm looking for even better . The Studer's great for certain kinds of Overheads or room mics (shiny expensive jazzy polished, 30 ips) or entire drum busses, turning signals and transients into textures, whereas the Otari shines on basically everything which needs a thick ballsy rock'n'roll attitude (guitars, basses, drums, vocals - everything !). OTR 499 30 0 for phat focus, OTR ATR 30 0 for smearing when required.
I just fell in love with the Akai Slow programs for heavy distorted guitar. There are one or two in particular but I can't remember which. I used to find them kind of dull but I've come to see the Fast programs as too shrill while the Slow ones glue extremely well and can be EQed very well.