Since I am primarily a burley smoker, I enjoy a blend that can be smoked all day, medium strength and doesn't wear out my palate. A blend that is enjoyable with repeated smokes. C&D's Pegasus is such a blend for me.
I like a dark, earthy, malty straight Virginia with no added flavorings.
I like a brighter Virginia mixed with tangy, floral, sweet Orientals.
I like perique and burleys in moderation, but I appreciate the nuance they can add.
No latakia, ever.
I like a decent nic kick, no bite - VA/Pers and Orientals mostly. FVF, McC Pebblecut, McC Classic Samsun are all favorites. Trying to find substitutes for the McC now, but haven't found anything quite as satisfying.
I'm trying to get into burley blends, mostly because of the nic content and tendency not to bite as much, but none have really spoken to me yet other than Solani Aged Burley Flake.
Yesterday I would have said no Latakia ever, but Presbyterian Mixture recently changed my mind.
The guy who taught me what I know about wine used to say "if you like it, it's good wine". I think the same applies to pipe tobacco.
For me, good tobacco is one which feels like a small luxury to get to smoke it. I don't really look for "bang for the buck" in a blend because pipe tobacco has a really low marginal cost (much less than a cup of coffee), and I don't smoke a lot.
As far as brands, I'm heavy into GL Pease blends and the Mac Baren HH line, though the real special occasion stuff for me comes from brands like Germain and Gawith.
I seem to enjoy non-aromatic blends with good burley or Virginia as base. As a change of pace, I like distinctly tobacco forward aromatics often with whisky, rum, liqueurs or vanilla flavoring. Loose cuts require less preparation, but a good flake, coin, plug, or rope is great when time permits. I don't seem to require nicotine, though a buzz can be pleasant. I don't get nicotine nerves when I don't smoke for days. After those guidelines, I depend on the blenders, and sometimes my own sense of mixing, for some surprisingly good smokes. I did a strong tobacco quest for a while, which was enjoyable, but now I am equally interested in medium and even mild blends, adding stronger tobaccos on impulse. A bowl or two a day is usually all I do, though I do several bowls on weekends on occasion, and skip a day or three if I'm busy otherwise. I don't smoke and drive, since I tend to be one track in terms of concentration. My thought processes are already multitasking as it is.
I seem to like most genres, so it's hard to describe what makes a tobacco good for my tastes. I guess there just needs to be something interesting about a blend to keep me coming back. That could be that I find the tobacco extremely satisfying (code for has lots of nicotine, probably) like Dark Flake U/S or Bold Kentucky. It could be that I love the interplay between the different leaf types in something like GLP Kensington. Maybe the way an added flavoring can bring out something unique in the same old ingredients in something like Bengal Slices Haddo's Delight. Sometimes I just find a blend comforting to smoke like a lot of the good burley blends out there.
I'm a simple man with simple tastes, so I reckon I prefer straightforward not too complex medium-strong Burley and Virginia blends, if there is topping then it has to be subtle and not masking the initial tobacco flavors too much,and yes Kentucky Dark fired is my favorite condiment leaf
Balance. I think that makes me a bit of a dinosaur, but I don't care for blends with too much going on. I prefer a harmonious whole to varied tastes depending on which leaf is burning at the time. This doesnt mean a lack of complexity, but rather, a consistency in flavour.
If a blend or single-leaf has a good flavor profile, the other primary quality is burn characteristics. Does it light readily, burn slow and evenly, stay lit, and relight easily. The less I think about ignition, the more I attend to the flavor and texture of the smoke.