whenever i upgrade my CAD workstation i choose the newest fastest processor i can afford at the time. What's imporrtant here is to look at the processor type. The newer and more powerful the longer it will last you in time.
For Intel this means:
i7- fastest
i5 - fast
i3 - for light home use
then you want to look at the model, so for example i use an i7-2600K, it's a pretty old processor but still good to work with (the K at the end means it is an unlocked processor which can be overclocked but i've found this to have little real world benefits except maybe for rendering). Each model will have different processor speeds and different amount of cores. But personally i think what matters most is single processor speed.
It's a bit techy but you can have a look here: https://www.cpubenchmark.net/ when you've seen a PC you like and want to know how the processor ranks, the higher toward the top of the lists the better and the longer it will last you.
for Graphics i recommend anything including or above a Nvidia GTX 960 (970, 980, 1050) which start at around 200USD. You can always change the graphics card which helps a lot with snappyness and rendering, i upgraded mine 3 times since i built my workstation and always got a reasonable price of the old ones on ebay.
i've recently looked at wether i should build a new PC now but to be honest after looking at the benchmarks and doing some tests with friends newer generation PCs i found that my old i7-2600k/Z68 is still only marginally slower than a new generation build would be.
More RAM is always good, 8 works but 16-32 is way nicer.
Make sure your satrtup disk is a FAST SSD, i recommend the Samsung 850 EVO series.
You can always build a better PC for less yourself, it'S really easy to do. When you buy a gaming PC you buy loads of stuff you don't really need. The compromise is always going to be in the quality of the components which usually means cheaper motherboard, lower specd processor and cheap hard drives.
An example:

so here the difference in price is 3 things:
1 - amount of RAM (8Gb vs 16)
2 - Hard disk capacity/type (Rotating platter vs Hybrid Drive i assume)
3 - graphics card: 1050Ti vs 1060
processor is the same: i5-7400 ... so it's some kind of mid range processor ... looking at the benchmarks it looks like my old 2600k from 2011 is still a bit faster, so not so fast a processor at all but useable for sure.
1/ 8Gb of RAM is more than enough for the beginning
2/ you want an SSD as a startup disc so fi i would buy this one i'd get an SSD and use the included drive as a data disc anyways. The 7200rpm speed is good but tboth of these will be cheap OEM drives for sure
3/ the 1060 is only going to be marginally faster, the 1050 is more than enough for Fusion and it's the TI version which has 4GB of VRAM which is useful
so you could safely buy the cheaper one here, but personally i would try to find one with an i7 processor that ranks a bit higher, maybe an i7-6800K
just a random example to illustrate but maybe that helps a bit
for the models you posted:
the 6700hq also seems to be a tad slower than the old 2600k, the 7700 a bit faster, but we're not talking huge differences here compared to a 6 year old model.
also note the processor speed and benchmark scores differences between the submodels of the 7700 series:
As for the 1060 graphics card, i think the 1050TI is a better deal at nearly only half the price. i personally don't think the 1070 is worth the money unless you want to game nicely in high resolutions. For FUSION i suspect the 300 USD difference won't make that much a difference.
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GENERAL DISCLAIMER: if there isn't a file attached to my posts then there is a reason for it. wherever i can i will attach a file for troubleshooting.If no file is attached i will always try to explain as clearly as possible with illustrative screenshots. when i have an issue that can only be helped by attaching a file which i cannot share publicly i won't ask about it here.