i5 vs. i7 - This used to make a huge difference, but today players wouldn't really be able to tell much difference between a higher end i5 and an i7, all other things being equal. Experiences with other games, especially those that can use more cores, will vary.
RAM - Technically no one needs more than 8 GB to run TS3 or TS4, but where having 12 GB or more comes in handy is so that one can run a web browser or other programs alongside of a paused game without having to worry about running out of resources. Of course we can always add more RAM later, but this isn't where I would be cutting costs unless I really had to, if I were shopping for a new computer today.
Graphics Card - TS3 would probably get some small benefit out of a GTX 1660/1660 Ti over a 1650. Can't really speak for other games, but if they can use more vRAM than TS3 can (and at just 800 MB that isn't setting the bar very high) then they too should benefit.
SSD - TS3 benefits from being installed on and having its user game folder on an SSD in that starting up, saving, CAS and Build/Buy category loading, and anything involving caching should run noticeably faster. Actual gameplay won't be much different. TS4 does not get this benefit from an SSD as it is programmed so differently. Experiences with other games will vary.
Although 256 GB should be fine, it's also easy to end up constantly working to maintain enough free space especially if one maintains and keeps feeding large CC collections. Even with the larger secondary HDD, I would find at least 512 GB to work with to be less limiting.
