Often easy for me to guide prospective tallit buyers, because when they tell me the type of tallit they are interested in, I already have a hunch what type of congregation they belong to, what level of observance they hold by, etc. I fully acknowledge that my impressions based on that type of highly unscientific data input are highly speculative, and therefore offer my advice with a grain of salt, pending further details.
When it comes to customers interested in buying a Gabrieli tallit I'm a bit more in the dark, because they run the gamut from Reform to fully Orthodox and the type of tallit they have in mind often varies accordingly.
Before Shabbat I received a fairly representative inquiry about how to buy a Gabrieli tallit, so I'm sharing the question and answer for others who might find it helpful.
I am looking at the Gabrieli Blue Joseph’s Coat Tallit. What is the difference in weight between the wool and cotton tallit? I am 5’9”. Would you recommend the 70” or 80” tallit? I want to get the Ptil Tchelet Tzitzit. Which style of tying is the most traditional one? Thanks for your advice. - Bobby S.
Shavua tov and thank you for your inquiry. The wool and cotton are quite close in feel and appearance. Wool probably holds up better over time and is less prone to wrinkling.
From a halachic standpoint, wool/acrylic is not recommended, and according to most opinions, wool/wool is preferable over cotton.
Most people your height would choose the 55 x 76 inch size, which I estimate would drape down in back to mid-thigh on you, but if you like it long and elegant (i.e. around the back of the knee) you could go with the 60 x 80 inch size.
If you have a tallit at home for comparison, measure it from top to bottom (i.e. from one un-fringed side to the other). It's probably 51 inches or 55 inches or 59 inches.
As for the tzitzit, if you are Ashkenazi (as your name suggests), I recommend you choose Vilna Gaon, Sefer HaChinuch or Arizal. You might want to refer to this post. The former rabbi of the Ptil Tekhelet Association used to advise people to go with Sefer HaChinuch.