just about any domestic engine. the SB chevy was always a great motor, even when it was choked in the mid '70's. they still ran great, even when neglected, easy to work on, will run w/ 1/2 its plugs fouled and its oil galleys plugged. great stuff.
I have to add, I disagree w/ the mazda fans. now, I DO like mazdas (on my 4th one), but I don't think they make the best engines. the 2.5 V6 in my '94 626's were ridiculous; only 162hp IIRC, 25mpg hwy (maybe) and req premium fuel! leaky valve cover gaskets less than 60K. I did like them, but I would do a 4cyl next time.
the 3.0 in my MPV is not too bad, but they have O-rings all over the place that you WILL learn to replace-often. known lifter problems, and of course, underpowered.
don't even get me started on the rotary...
I have to disagree on the saturn comment also. the SOHC 1.9 has known head cracking issues, besides the oil consumption problem. yes, it has a chain, but they WILL fail when the oil is neglected.
the DOHC 1.9 only has the oil problem, the head is reliable. simple ignition, easy to work on also.