Oh no no no, don't give up on D3 that easily if you haven't put in the time! I have 3 copies of that game still after giving one away and I've played it since it's release. It's a beautiful game. The point is to work your way up. Once you can handle Torment 1, the loot game will pick up. There's no need to rush it, finding the gear is the whole point. As you gain paragon levels, you'll become much more powerful anyway, especially around paragon 100 which comes a lot faster than you'd think.
If you absolutely feel the need for better gear, the quickest thing to do is blast through some bounties. The horadric cache from Tyrael can give you some really great rewards; the Royal Ring of Grandeur is the most sought coveted item from the cache. The biggest thing however, is using the shards to gamble at Kadala. With a little luck, she'll give you a few set pieces and you'll be well on your way into torment levels.
Damn you. Now I want to go get another 50 paragon levels or so. They had just added some huge updates last time I signed in too..
I have my wizard running around at T7, with paragon around 250 or so (seasonal char). I had the Ring of Grandeur in the Cube (so I can wear Focus/Restraint), which helped me get the 6 set bonus for Tal Rasha's. I also had the boots in the cube that double/quadruple the Tal Rasha's meteor's damage. I've been hunting down Ancient gear from Kadala and Rift Guardians (I find the four bonus chests from Tyreal to be disappointing, I just use that for the legendary crafting mats that are specific to each Act).
I can't find any decent gear, and the best I can solo (within the time limit) in Greater Rifts is around level 25.
Get the ammo scrounging perk. I believe it helps with finding cores too. Look for the generator things in buildings and remove them from those. Steal from brotherhood. Swap cores out when you are < 5-10% charge. They still sell for the same rate. Buy them from retailers whenever you see them. Max the intelligence skill that makes them last longer (goes up to making them last 2X as long). Oh, kill all robots, especially the big strong ones. I think that I got 3 off of one of them.
Even if you're in the Glowing Sea, always exit the power armour when there's less than 5% left in the Fusion Core, and swap it out for a fresh one. You can get up to 200 caps for those near-empty cores.
The Nuclear Physicist perk, which requires 9 Intelligence, helps a lot with their duration.