1n feels more solid, Eos 3 has more useful features, some improved control functionality and noticeably faster continuous rate. Feels less solid though as for the 2% difference in the finder accuracy, that's neither here not there.
Beware buying used and check thoroughly. 3 out of 4 of the used SLRs I have bought had faults. One did not focus accurately, one had the detentes missing from the command wheel (functions fine) and one had a command wheel that did not function but felt like it should!