AI choices are mostly letrozole, anastrozole/Arimidex and aromasin.
Anastrozole has a good predicable dose/response for most guys.
Letrozole is harsh and dose/response is not very predicable, stay away.
Aromasin is more expensive to use than anastrozole and a higher chemical load on the body.
A few are anastrozole over-responders who need to use 1/4th the expected dose. So very cost effective once that is figured out.
Anastrozole is a competitive drug and needs to match ones serum T levels. This makes dose adjustment calculations very easy as explained in the stickies. You can calculate a E2 level change and a T dose change at the same time and be on target. Until you get labs while on anastrozole, you simply start using the suggested dose of 1mg per week in divided doses for a 100mg/week T cyp/eth dose. When using transdermals, your T levels are not dose predicable, so anastrozole dose is a crap shoot.
A very few don't need an AI.
Lab work and AI dose corrections will take guys there if needed.
If your E2 was not low before TRT, it will be higher than optimal after TRT without an AI.
Without an AI, on TRT, many feel great for 4-6 weeks then crash on E2 with many of their TRT symptoms returning.
You need to work these things out yourself because of individual variations in TRT and AI response. Your doc may not be useful; if he cares about E2 at all. Docs mostly do not understand more that lab numbers and are confused by symptoms. Many docs will think that high-normal E2 is just normal!