i am into r31s obviously. so call me biased.
but i can't go past the rb30e.
mine has only bout 205. i have absolutely abused the car since i bought it at 136,000. that was 2 years ago. it has sat on rev limiter for a total of about 2 hours at a motorkhana day. it's done 4.5 minute burnout in 1st gear at 6,200 in burnout pit at wsid. various others engine harming experiences where it just bounces right back.
i'm not known for engine maintenance, but car does not miss a beat
the rb30e is amazing
we know of a guy with a 31 that was done 700,000. no kiddin.
anyway i'd go so far as to say it's definitely the best engine in this country ever, if not the world.