Confirming some cities you mentioned. I would say rumor has it that Europe, Asia and South America are the places to be for the hottest trans action. However, I only have first hand experience in Europe. Specifically; Amsterdam & Rotterdam, Netherlands, Paris & Nice, France, Rome & Milan Italy, Barcelona, Alicante & Ibiza Spain, London, UK and a few other places. Also, Rio De Janeiro, Brazil is safe and the trans women are amazing as well as Medellin Columbia.
Most of the women in Europe I've seen were usually South American; Brazilian, Colombian, Ecuadorian or Venezuelan. Depending if you're looking for top, vers or bottom girls may also help guide you to the right country. Travel through Asia is relatively safe but parts of South America aren't. Travel to Brazil, the big cities Sao Paulo and Rio or Medellin are safe if you stay in the central city parts. The further out the more risky. The risk is similar to Asia, you might get pick pocketed or something stolen from a bag or back pack or ripped off by people looking to over charge you for touristy stuff, restaurants etc.
Bogota Columbia is not quite as safe as Brazil or Medellin, but again in the central city areas it's the safest. Ecuador and Venezuela are considered dangerous for Americans to visit. Even in the big cities there are more potentials for danger and it's more than just pick pockets and thieves. The best thing to help you in any South American Country is knowing the language well without a translator whether Portuguese or Spanish. The more you look and act like a tourist the more risky it is for you.