I've had an '81 245 and '73 and '74 145e's.

The difference in suspension is almost entirely in the front.
The 145 had unequal length a-arms, normal shocks, and numerous pivot points.
I prefer it, even though it is more work to rebuild. Even with the worm-and-roller steering box, I think it handles bumps and corners better. I upgraded the front sway bar to a IPD. The 240 has strut front suspension, which has fewer pivot points, and I don't think they feel as sure, for some reason. Maybe the forces aren't spread around like the 140. It may be that there are limitations to the strut geometry. When the 145 is jacked off the ground, the wheels tilt in at the top visibly. I think that might position it for a more solid landing when it comes down. I also can adjust my front suspension (caster, camber), which I never could on the 245.

I also like seeing over the hood more easily in the 145.

However there are 1992 245's which are 18 years newer than the newest 145. I'd take one of those, if the price were right. I think 245's rusted more than the old ones, too. My 245 rear floors were gone in a few years. It was before I had the savvy to catch such things early.

The engines... The b18/b20 head is cast iron. IMHO the only major engine casting material, if longevity is key. HP is tolerable and can be bought.
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'74 145e T-5 'Orange Alert'