The most important question when deciding what lens to get(and a total wonder why people don't ask it on this forum) is... what are you shooting or what do you like to shoot? Different lenses have different uses. I don't understand people who get lenses just because its 'better'. So many 70-200 VR2s get thrown into BnS because people realise postpurchase that they don't need one or its too heavy. Get lens that suits your current needs.
You mentioned a 'better zoom', a preference for f/2.8 and a budget of under $1000 so I'm going to work loosely off those constraints.
If the aim is to replace your kit lens, a 2nd hand 17-55mm f/2.8 would work.
If the aim is to extend your reach, 70-300mm is available(no f/2.8 however). Sigma's 70-200mm is viable, but only if you really want to keep it. IIRC the resale on the 70-200mm sigma is pretty much nonexistant. Also, its probably over 1k and is pretty damn heavy.
If you're shooting mainly people and/or scenary, consider the AF-S 50mm and AF-S 35mm f/1.8. There's no 'zoom'(move your feet instead), but the performance of primes is superior to that of your kit lens. You can get both for under 1k too.
There is no modern 50-300mm(only an AI-s version). You might be thinking of the 55-300mm. The 70-300mm is also better than the 55-300mm