Having been through a bajillion knobs, myself, I've only settled upon the plain ol' '93 Cobra style knob. It's basically just a leather-wrapped version of the standard rubber/plastic knob found on most Fox 'Stangs. It's light, fits right in one's hand, it doesn't get all hot or cold in summer/winter, doesn't transfer driveline heat, doesn't buzz or rattle, doesn't unscrew itself every other time you shift ... it's just all-around coolness. Plus, it looks really darned nice in that it blends in perfectly with the stock shift boot.
As far as those Hurst T-handles go, I had one for a week before I ditched it. You have to buy the one that specifically says on it "For Camaro/Firebird/Mustang" on it, because it's something like an M12x1.5 thread, whereas the "Universal" ones are always SAE threads. If you've got an adjustible shifter handle to thread it onto that puts it at a different angle, or if you've got long arms, then it might work for you, but I could never get the thing to sit at a comfortable angle for me. Plus, the stupid thing kept coming loose and unscrewed every other time I drove, no matter how well I kept that jam nut screwed up against it - even Locktite didn't help. And, of course, there's the usual problems with heat transfer and hot/cold seasonal temps.
I'd like to try one of those fancy weird composite-material knobs that UPR sells sometime. They're shaped funky, but the material they make them out of is awesome stuff - no temperature problems - and it just screws right on there like most other knobs.
Ball knobs are nice, but like you said, they tend to leave a gap between the knob and the shifter boot. The Bullitt shift knob does have a shaft as part of it that takes up the gap, and it does feel really nice - not super-fat like those 8-ball knobs, but still fits right in the palm - but again, there's the usual problems with heat/cold that all aluminum knobs get. Maybe if you dipped one in some of that Plasti-Kote stuff you use to make rubber grips for pliers and stuff...?
