Although by no means and under no circumstances this word is used as honorific nowadays, in phrases like "Это мой товарищ" there's no hint of any political or historical connotations. It is quite common usage of this word, though it word "товарищ" is less used nowadays than word "приятель".
Sometimes, especially while appealing to a group of people (...
Below is a definition of the word Рекомендовать from Словарь иностранных слов. As you can see, unbiased recommendation (3.) is now marked as outdated. Modern meaning is "I recommend you X, because he/she/it is useful/beneficial to you:
РЕКОМЕНДОВА́ТЬ, ду́ю, ду́ет, несов. и сов. [польск. rekomendować < ср.-лат. recommendare < лат. mandāre поручать].
Товарищ sounds more ironic these days. I'd agree on this point, it's been already mentioned here in the thread. Also it is used in the military when talking to an officer.
If you need an equivalent to mister, I'd say there's no such word nowadays. Some were in the past (товарищ, господин, сударь), now not.
In a conversation with your friend you can use друг, ...
Some folklore you might consider useful.
When someone hypocritically address to other as a товарищ, he might get as an answer:
«Тамбовский волк тебе товарищ».
«Гусь свинье не товарищ».
However, these phrases were known even in Soviet time.
Nowadays, господин/госпожа are for sure acceptable, though one has to keep in mind - that these words are extremely official.
So during common conversation you should avoid these words. Господин/госпожа applicable in official messaging or if you want to address someone extremely officially, e.g. Mr. Petrov, we are going to arrest you/г-н Петров, мы ...
Short answer: It is fully equivalent to Mr./Ms. nowadays.
Long answer: Господин/госпожа is a modern polite address, to be combined with the last name.
A possible polite address is also first name + patronymic if you know it. It's more polite, but also somewhat closer. Not a clerk to a customer, but business partners to each other.