https://pcpartpicker.com/list/Fzfv8K
This one has a pretty solid upgrade path and only cost 640$.. The previous post list above looks good, but one key issue is that you will definitely not find a 1060 6gb for that price listed. They are going to be minimum 400$ and most likely 500$ range. GPU's are very overpriced right now because of bitcoin miners screwing with the demand. You can get a 3gb version for under 350$ if your lucky.. Just to give you an idea of how much they are inflated.. The 1060gb should not cost more than 300$ at the most, typically you buy them 200$ and 250$ would be high. The 6gb should cost no more than 350$ and that might be a little on the high end. RX 480/580 should be 220-350 at the most depending 4gb or 8gb versions. Price are nuts.
Some of the lower models are not as badly inflated like the RX 560 and GTX 1050ti.. The 1050 you can get for 200$ range which is high, but normal price was somewhere around 170$-180$ when they came out. RX 560 is 170-190$, but should cost no more than 150$ and the 1050ti is much better performance anyway.
I have a 1050ti on here which is a great card for 1080p gaming. Games like BF1 and Doom get 70+fps @ 1080p on medium / very high settings respectively. Witcher 3 gets 60+ on medium, Project Cars is a little lower in the upper 40's on medium 1080p, but that is with 4xAA on. You turn that down or turn settings down you should hit 60fps. If you can find a GTX 1060 3gb for 270$ or less it would be worth it. This build is only 640$ which gives you an extra 100$ to spend on a more expensive GPU, I just don't think you will find it right now at a reasonable price. The 1050Ti the best for the price right now.
http://www.tomshardware.com/reviews/nvidia-geforce-gtx-1050-ti,4787-5.html
I don't know your exact situation and future plans, but what I would do is buy the 1050Ti right now and save the extra money instead of overpaying. Use it for the next 18-24 months or longer and then buy a new gpu. The get more efficient and way more fps each year for the same price..
I bought a R9 270x a few years ago when I first switch to PC gaming. I could not get 60fps @ 1080p in everything, usually I had to settle for 45-50fps on low settings at 1080p or I had to play at 1600x900. I remember trying to play witcher 3 and i had to settle a lot on quality / resolution. It was not a bad card for 200$ range, I was happy with the purchase. Fast forward roughly 2 years I kept that card and I buy a RX 480 for only 20$ more than I paid previously. This card wow it runs everything maxed out settings 60-90fps on everything. All the newest best looking games it easily runs them maxed out very well. The technology just keeps getting better and better, but prices don't really go up. Instead of overpaying now by 100-200$+, just replace your GPU in roughly 2 years or so.