First of all, srry for my English, I'm brazilian and I don't write in english for a while now (One of the main reasons I joinedthe forum today is to startinteracting in English with some people and make it better).
I've started playing minecraft a long time ago (since the later alphas) and still loving the game, but, sometime it gets a little bit boring (specially because a play most of the time alone), so, I started playing with mods, a then, with modpacks. Here my top 5minecraft modpacks and why:
1. Tekkit Classic: This modpack is my favorite of all times. It is one of the first minecraft modpacks I've ever played. It's based basically in industrial machines, with mods like Industrial Craft and BuildCraft, but it has some magic mods, like ThaumCraft. This is an old modpack, but it is worth. This one is really fun and have so much to do. You can spend hours and hours with it without getting bored, specially when you play online with friends).
2. The 1.12.2 Pack: Basically an Tekkit Classic mod upgraded to 1.12.2, with many new stuff, but unfortunally with many things missing too. It has less servers and isn't as popular as Tekkit Classic, but still bringing areally good experience and good times in minecraft. One of the biggest diferences between this one and Tekkit, is that this pack has more dimensions than the vanilla, has a progress system, and of course, is based on a newer minecraft version.
3. RLCraft: RLCraft is a hardcore modpack, created to elevated considerably the game dificulty, basing the gameon realism and reallife dificulty to do things. This is for pros or people that like a really hard game experience.
4. Skyfactory 4: Sky Factory is a Skyblock based mod with a really good and well done progression system. It has many mods, starting by simple mods like BiblioCraft to very complex mods like Project E. It is one of the best modpacks with you like to start from nothing and follow the progression system or quests till you do everything (it will take a lot of time)
5. Farming Valley: Farming valley is a modpack with a mix of mods that create a progression system and a gameplay style Harvest Moon and Stardew Valley games. If you like this games as much as I do, worth the try!
RE: Bored with Vanilla Versions?? Here's my top 5 modspacks
I highly recommend you checkout SEVTECH Ages! I played it a while back and it was the most fun I have ever had in a modpack. It was challenging and intriguing and I really love how they locked items and crafting recipes to force the progression feeling. I don't want to spoil to much but highly recommend trying, it was the most fun I have ever had playing modpacks and I've played quite a few