He was a popular leader because under his rule Yugoslavia somewhat more united than after his death and before he came to power. Yugoslavia made huge advances during Tito's time in power. His government enabled huge masses of previously poor people to have access to education. Pretty big chunk of infrastructure, railways, road network, electrical network, communications etc. was built during that time. Country went through a rapid industrialization. Tito's goverment was smart enough to make a break with USSR early on and to steer a course somewhere inbetween East and West, which was a sweetspot durng the cold war, as it permitted them to do business with both sides in the conflict. Citizens could travel freely to both eastern and western bloc countries. Yugoslav passport was one of the rare ones that would get you easily from East to West Berlin in that time. Arms exports to other 3rd world countries become a big moneymaker for Yugoslavia.Crime rate was very very low under his rule as well.

A number of reasons:

The relatively liberal economy. Tito and Yugoslavia had good relations with East and the West. You would be surprised at how infringed people feel when they are unable to drink Coca-Cola, or unable to smoke Marlboros. This was not the case in Yugoslavia. When a Yugoslav travelled to the West, there was not much that was unavailable to them in their home country that they could see while on their travels. The few that were able to travel from the Eastern Bloc to the West, did not see this. In fact, many people from the USSR travelled to Hungary, where they could purchase illegally smuggled Western goods from Yugoslavia.

The country rapidly industrialized. Yugoslavia was primarily an agricultural society prior to Tito. For example, a number of Western reporters throughout WWI commented how going to Serbia was like seeing a [romanticized] Medieval European country. Not much changed in the interwar years, but with Tito, rapid industrialization commenced.

High standard of living. People from Czechoslovakia, Romania, and Poland, to list a few, regarded Yugoslavia the way people regard the USA/Canada/Australia today. A paradise where you get what you deserve, can provide for your family, and even afford some luxuries. They still held true to some socialist values, maternity leave, extended vacation time, free education (entirely, including university). He also implemented a workers ownership model for the economy. I am not an economics expert, and hesitate to delve into this, but it functioned exceptionally well under his rule. People lived well. It's hard to get upset when you have a full tank of gas, a fridge full of food, running water, Marlboro, imported beer, Coca-Cola, and a coast to go to every summer.

The military. Yugoslavia prided itself as being the fourth largest military in Europe. For the various (and large) arms exports the country did. Serbs in particular had a very warlike history, especially in the 20th century, and this was very important to them on a psychological level too.

Ability to travel. You want to go to the US? Sure. Canada? Sure. China? Sure. France? Sure. USSR? Sure. You want to go near anywhere in the world, go for it. Ironically, in terms of visas, this is true for Serbia even today (in large part because of Yugoslavia), but people can't afford to go to, say, Paris. Back then, people were able to do both. For the Warsaw Pact, both served as impediments.

Education. I already said how education was free at all levels. What I didn't say was how it was used by Tito to enchance his image. There was no "politics" class in Yugoslavia. It was a Marxism class. You wouldn't learn much about any individual ethnicity in the country, but history would start with the Partisan uprisings against the Germans (led by none other than Tito), after a brief mention of just how terrible the Kingdom was and how the King abandoned his country. Tito used the educational system (as most countries do) to forward his own, and Yugoslavia's (rather than Serbia's/Croatia's/Bosnia's/etc...) image.

He was a war hero. Enough said, people love war heros. Charles de Gaulle, George Washington, Juan Peron, Hitler, Castro, and Tito amongst many, many others.

The Non-Aligned Movement. It's one thing to stand up for yourself and reguse to be another's puppet (like Tito did with the Yugoslav-Soviet split), which appeals a great deal to numerous ethnicities that had been oppressed by large empires for centuries. It's another thing all together to gather all the countries that are doing this, and start a movement to protect every such countries interests. This is precisely what Tito (along with Ghandi, and Nasser, did). There was no lack of admiaration for this.

These are the main reasons why he was loved in Yugoslavia.

Now as to your original question, and comparing to other leaders of the EAstern Bloc:

First: Yugoslavia was not part of the Eatern Bloc (since 1948). It was a socialist state, but not tied to Moscow in any way.

Second: Off the top of my head, Zhivkov of Bulgaria was well liked in Bulagaria until the 80s. Krushchev was well liked in the USSR. Even Stalin was relatively well liked in the USSR until he died. Tito was an anamolly in that he was so loved globally rather than domestically, throughout his rule.

Third: For countries such as Poland, Lithuania, Latvia, Hungary, and Czechoslovakia, you have to bear in mind that they felt occuppied by Moscow. Yugoslavia was not. Even in the first three years after the war, Tito was given a free hand for near anything and everything by Stalin. You'll also see that there is a correlation with how close each country was to the USSR geographically, and how much they were dissatisfied with their rulers. The closer, the more dissatisfied. Bulgarians look upon their communist era rather fondly, while the Polish...well...let's just say they don't. This is primarily because the further away you are from Moscow, the less likely Moscow would violently retaliate.

Fourth: Why is Tito remembered so fondly in Yugoslavia as compared to other Eastern Bloc countries (a slight spin on your question). Yugoslavia's economy collapsed, and then civil war broke out. Who would not remember a time when everything I mentioned in the beginning of this post fondly if this was what had followed?

What followed in the rest of Eastern Europe? Market liberalization, democracy, independence from Moscow, visa liberalization, Western products.

They had better times follow, Yugoslavs had the worst time since WWII follow. You look back on your immediete past, if it's better than what you are going through in the present, you will see it in an idealistic fashion.

EDIT: everything /u/terekkebab said is true too, so don't dismiss his comment, I just expanded a bit on it.