I did have the FM2 and FE cameras because they were part of the system I was using. Mostly back-ups for the F4/F5.
I've always thought the OM4T was the greatest camera Olympus ever made and is much more camera than the Nikon's.
If I was picking in this day and age I would go with the OM4T. Great spot metering, great construction, well thought out system.
The only advantage of the Nikon's is the availability of used items and lenses. Some of the exotic Olympus lenses are very hard to find. I remember seeing a 180 f2 at a news photographers trade show years ago, but have never seen one come up on ebay. Not that I'm watching every day.
If it was my money I would go with the OM4t.
The OM-4T is the more sophisticated camera, well built yet light which is a big consideration if you travel a lot with your gear. As long you are not on the hunt for exotic lenses, Zuiko glass can be quite reasonable.
As availability of spare parts will eventually become an issue, I'd be inclined to favour the FE2. There are far more of them around than OM4Ti's (at least here in the UK) It also wins out on the grounds of "the simpler the electronics, the less likely it is to fail". I've used FE2's, FM2's for years, they handle well, are solidly made to last a photographic lifetime.
Also, do you really need to take eight different spotmeter readings before exposing?...By the time you've done this, the picture opportunity is likely to have disappeared.....the sun's gone behind a cloud etc. etc. .....In my experience, in day to day photography, these complicated metering systems just don't get used.
Quote from Camtech: " OLYMPUS NO LONGER OFFERS FACTORY SERVICE FOR THE OM-3Ti or 4T/Ti champagne body. It is likely they will soon discontinue 4T / Ti Black service."
The OM4Ti is a much more valuable camera than the FE2. It was made to compete with the F3. For actual use I rather use the FE2.
For repairs you might check out KEH.
If your use to your existing Nikons, then the new one will be intuitive and less chance of missing a shot.
As I used my OM4Ti for landscape photography generally I was very happy with it until I took up street photography covering parades and found that I could not focus fast enough to capture what I wanted. By the time I focused the expression on the subjects face had changed or the action was completed. It was then that I invested in an auto focus camera the Nikon F80 ( I now use the F100) but I still use the OM4Ti for my infrared photography which is still landscape based.