On a crop camera, 50mm and 85mm are the two extremes of the "ideal portrait focal lengths". There are many to choose from, many of which are at least 1 or 2 stops faster than the 90/2.5 Tamron Macro.
Sure, you can use shorter and longer lenses... but these are the "traditional" focal lengths, felt to be ideal for the way they pleasingly render faces without distortion.
I am not a big fan of using a macro lens for portraiture. Macro lenses give one type of look, portrait lenses another. Part of the difference is the flat field design of macro lenses, another part is the larger apertures available on more portrait oriented primes.
Using a crop camera such as the 60D, an interesting lens that might serve both purposes better is the Tamron 60mm f2.0. It offers a full stop larger aperture than most macro lenses, so addresses at least partially the differences I see between macro and portrait lenses. I have not tried it yet... mainly because it's a crop only lens and I use both crop and FF cameras, so would prefer lenses that can serve on both, but am very tempted to make an exception for this particular lens.
If you don't shoot a lot of macro, if portraits are a higher priority...a non-macro "portrait" lens might be a better choice, along with a set of macro extension tubes for occasional use. I've often used them on 50mm, 85mm, 24-70 lenses. The Kenko set is good. So are the Canon tubes that are sold individually. There are other, good tube sets that are a bit less expensive.
There are times when a zoom is nearly essential for portraiture (kids, pets, anything where you respond quickly). On a crop camera, 24-70/2.8 is a near ideal portrait lens. In fact, I like it better for portraiture on a crop camera, than I do on FF. Still, it's "only" f2.8. And the Canon 24-70/2.8 is pretty expensive. However, there are some excellent third party 24-70/2.8, too, that might serve and cost a lot less.
The 70-200/2.8 is a pretty good portrait lens on full frame, but a bit long much of the time on a crop camera.
I would not consider an f4 lens for portraiture. The 70-200/4 is a super lens, plus is smaller and lighter than the f2.8 version... but it's still relatively large and intimidating. In fact, all the "big white" Canon lenses are a bit intimidating for use with non-professional models.
The 135L is a super portrait lens on FF... it's a very long portrait lens on a crop camera.
28/1.8 is a good group portrait or environmental portrait (showing a broader view of a person in their surroundings such as a workspace or home). It has to be used very carefully to avoid wide angle distortion issues.
BTW, I also use the vintage Tamron 90/2.5 manual focus lens... the Adaptall 2 version... with a "chipped" EOS mount (bought from China, via eBay) so that my cameras' Focus Confirmation still works. It's a good lens, but I mostly use it for macro. Mine is the smaller 1:2 version (all the f2.5 might be, I'm not certain), which I often use with macro extension tubes to get closer to 1:1 magnification. I don't use the matched Tamron 1:1 adapter, it's a pain to use because it fits in between the Adaptall mount and the lens. Standard EF mount macro extension tubes are much easier to use.