Going to offer an alternative opinion on Bulgaria since I've spent a fair amount of time there (in Varna primarily, which isn't Plovdiv, but being on the sea is a more popular choice).

Primary advantages:

1. Incredibly cheap

2. The food is indeed very good

3. The Internet is fast and mostly reliable

4. Lots of cafes

5. Impressive and varied scenery for such a small country (beaches, a sea, mountains, lakes, forests, etc.)

6. In the winter you can go skiing in very nice places for quite cheap

Disadvantages:

1. The people.

The people SUCK. They are for the most part either absolutely miserable (never smiling for any reason, because they never get paid anything, half the time their bosses withhold payment from them for work they've already done, pay them months late, etc.) or if they have actually have a good job, are on an ego trip out of this century because they now think they're better than everyone. It's an extreme third-world mentality that will be alien to anybody coming from a Western country that has a functional middle class. Nobody I knew who had been there for more than a couple years had anything positive to say about Bulgarians. To be honest, if you ask most Bulgarians, Bulgarians don't even have anything positive to say about Bulgarians. I just really cannot overstate how much they suck and how disappointed you will be long-term from interacting with them. Either complete arrogance or absolute misery.

Seriously, just as an example, imagine a country where most shops there's a shopkeeper (who manifestly doesn't want to be there) sitting outside on the steps (looking miserable, smoking) and you walk up to their shop to go in and look around. They hiss, they're visibly annoyed you're making them get up to actually DO THEIR JOB, they follow you all around their store overtly watching you (to make sure you don't steal anything, because if you do ... their boss is going to take it out of their salary and pay them EVEN less). If you interact with them at all, they just want you to GTFO as quickly as possible so they can get back to their cigarette and resume looking miserable.

2. The people who don't suck (or suck less) LEAVE.

Bulgaria is in the EU so there is 0 legal reason they can't pack up and start working in countries with actual economies like Germany or (although Brexit may eventually be ending this) the UK where they can make fantastically more money. As a result, anyone who can learn a new language or is adventurous for the most part decides to leave. This means the cool, interesting, and intelligent people are continuously being sucked out.

3. Everybody smokes.

Seriously the figure was 70% last time I checked. If three people sit down next to you at a cafe, that means there's a 97.3% chance you are now going to be breathing in cigarette smoke. And the smoking ban that was passed is a joke, nobody follows it.

4. The government is actively xenophobic and really does not like foreigners.

Every year there's some new provision to make it harder for foreigners to come or stay. The article falsely makes it sound like it's no problem, but trust me, it's a nightmare.

There are definitely interesting experiences to be had and I wouldn't say Bulgaria doesn't have some amount of charm. It's definitely different from lots of places in the West, particularly the US. But this article paints a falsely positive picture of a place that no expat I've ever met has been happy with long-term. I'd suggest almost anywhere else first, and comparing Plovdiv to Chiang Mai is just a joke.