I'll chime in with the others on this topic.
The combat update is the biggest change to your game feel, in my opinion. In addition to attacks having a cooldown timer for maximum usefulness, you now have an offhand. Remember how we used to have a mod to be able to right-click torches while having a pickaxe equipped? No more! Equip torches in your off-hand/shield slot, and you can do so without issue! You *can* also equip a shield in your offhand if you like, I think Thermal Foundation makes some more interesting shields than the vanilla one, but other than fending off the arrows from skeletons (who got upgraded with aimbot), there's little use to it compared to the utility granted by some of the mod-added off hand tools.
Some suggestions and mod callouts as popular these days:
* Astral Sorcery is a lot of fun. Consider it similar to how Blood Magic used to work, but with a less creepy vibe to it. You need to build a structure to perform your rituals, and as you progress, it gets bigger and bigger. It has some grinding of resources required to get anywhere, and the fun toys don't start unlocking until after you have a couple of tiers under your belt. Granted, the actual stargazing and drawing of constellations is kind of a pain the first couple of times when you don't really understand which constellation you are looking at by the placement of stars, but it really is enjoyable overall.
* Thankfully, you missed the days of EnderIO-ology. These days, people now are driven to Actually Additions for their 'do anything you want and get away with it' mod. It has everything you'd want from a tech mod: wireless transmission of power/fluids/items, a simple but effective sorting system built into the item routing system, a stupidly easy and powerful early game power generation system (Canola FTW), and a drill that makes all other mining options completely obsolete. Oh, and it has worms, which gives buffs to how fast crops grow in a 3x3 area, and greenhouse glass which gives another buff to how fast crops grow that stack with worms, which means a relatively small plot can easily be maintaining a 1k RF/t setup without too many troubles.
* RFTools is amazing, and I suggest you check it out. Most people do it just for the teleportation network system, but it also has RP2's level of logic gates, a Builder (that can also quarry), a trans-dimensional power transmission system, and more.
* Remember Thermal Expansion? Well... it's expanded, into what is now called the 'CoFH Suite'. And holy heck has it expanded! First off, you have CoFH World, which is one of the best worldgen and orespawn systems I've ever used. Then there's Thermal Foundation, which can be further used to consolidate what sorts of ores spawn in world so you don't have like four different types of copper spawning that don't stack with each other. Thermal Expansion you are already familiar with. The ducts and pipes, however, got shifted to Thermal Dynamics, and got some amazing logic built into it. It is almost, but not quite, on par with Logistic Pipes for storage sorting, but it doesn't have any auto-crafting mechanic, or any way of accessing the entire network's storage from a single location.
* Applied Energistics/Refined Storage. These two have essentially replaced Logistic Pipes in the niche of 'I want my entire base's storage centralized and accessible and able to auto-craft and handle sub-combines automatically'. Refined Storage is less complicated, AE2 brings complexity to the table as part of its design. Pick one, don't use both.
* Industrial Foregoing. MFR is no longer being developed, this is the natural successor. Plus a few extra tweaks.
* Immersive Engineering. If you like big multiblocks to do your work instead of small 'magic block' machines, then this mod is most definitely for you! It carries with it a really awesome steampunk vibe with its graphics, and you can almost hear a certain
tune playing in the background as you are watching stuff be carried along on conveyor belts from big machine to big machine. As you get into the mod, it just keeps getting better, with the ability to refine Biodiesel from seed oil and ethanol which can feed into a fuel-hog multiblock generator that can crank out 4k RF/t. It also includes an Arc Furnace which requires graphite rods that need to be periodically replaced but can very rapidly smelt metals and even make alloys.
* While Agricraft has gone by the wayside unfortunately, the cooking scene has been completely overhauled! First, we have Cooking For Blockheads, which gives you a multiblock kitchen to prepare foods in, but not really able to be automated. I personally really enjoy this mod. And to give you something to prepare other than baked potatoes, we have Pam's Harvestcraft which adds in a TON of new food items and crafted foods.
* Instead of NEI, we have JEI, which is less cluttered. But don't worry, if you want your overlays back, there's a mod for that as well, which I believe is included in the DW20 pack. There's also a mod called The One Probe which gives you a lot of the information that WAILA used to provide.
* Finally, I'm sure you recall Factorization's Barrels, that being the only part of the mod that most people used, and the follow-up JABBA which was heralded as pretty neat. Well, we now have the ultimate iteration of that storage method, Storage Drawers. The fun thing about this mod is that you can have a Drawer Controller which can be used to automate the input or output of all connected drawers, up to like a 12 block radius around it.[/URL]
