What keeps me driving Datsuns? Thats a hard one because there are so many reasons.

Economy of purchase.
Lets face it, they are cheap to buy, even if some classic models are becoming dearer.

Economy of operation.
Cheap to drive, cheap to service & maintain as well as to repair.

Economy of effort.
No need to wrestle a steering wheel in a Datsun. By way of comparison, Drive a stock 910 Bluebird, then go straight to a same year Sigma. It drives like a truck.

Interchangeability.
Look at the tech section & various posts. There is very little in there about aftermarket stuff. Want a stronger diff? Use another model Datsun one. Upgrade suspension & brakes, same again. More power? A later Datsun swap will fix that problem. It just goes on & on.

Excellence of Design.
Just think about it. That little 1000 engine, designed on the cheap back in about '64/'65 was developed into the larger models that are legendary for power output & reliability. They are such a good design, that they are still in production forty years after the first of them went on sale in 1966. Not many engines can claim that.
These engine will take boost in stock trim without too much fuss & those who race, as well as those who drive a lot will know from experience that as long as there is oil in the sump, you CANNOT kill the bottom end.
There are many owners of newer fancy-dan exotica who came to realise that DATSUN spells eat-my-dirt, yet this economy engine shares much more technological commonality with a mid '20's Chevrolet than anything that you will find in a recent model car.

Variety of hardware.
Want an A series engine? They came in six basic sizes [A10, 1200/A12, A12A, A13[two versions] A14 & A15.] There are about five or six cylinder heads, including GX & factory race types. If you want power, or economy, or somethin in between, then there is a combination of A series engine parts that should fit the bill, & all at a very modest cost when compared to Datsuns contemporaries.
There are three basic manual transmissions [light, stronger & bulletproof] & the light one was made in three speed, four speed, & five speed with three ratio options in the four speed, & two in the five speed. The mid size one had direct drive or overdrive five speeds.
If you have a 1200 or 120Y there are up to three rear axle choices,[H145/150, H165 & Warner] with three [Jap] diff sizes,[H145, H150 & H165] a wide range of diff ratios from somewhere near 4.8 up to 3.54 to 1 & LDS's were made for all of these.[aftermarket only for H150]
Even the engines came with single carbs, twin carbs, & EFI. Name your poison, & take your pick. Chances are that it will have a Datsun name on it & lets not go into suspension & brakes as this post is too long already.

Reliability.
Now, if you want to kill it, you will find a way, but operate your Datsun within reasonable limits & it will soldier on till the sun grows cold.

Soundness of design.
This is the final reason for me. They were a GOOD basic design back then & nothing has changed since.
They are simple, reliable, stylish, fixable, sound, inexpensive, & modifyable.

Thats why I drive a Datsun