I've been using Olympus OM bodies and lenses for 45 years, and heartily recommend them. That even includes the bodies that require more frequent change of batteries - my OM-2s has been a warrior since I bought it new, and keeping a couple of extra batteries on hand is easy, and in recent years when I've owned OM-1 or OM-1n bodies, the battery adapters are cheap and easy to use.
Does the size difference between the two lines matter to you? The OM lenses are also usually smaller than their Nikon counterparts.
That being said, if you like the Nikon mount lenses you have, and like the Nikon film bodies available to you, than I wouldn't recommend against them for you. I just wouldn't like them as much for me.
To provide you with context, my current OM kit includes my favorite three lens kit - 24mm f/2.8, 35mm f/2, 85mm f/2 - plus my choice of OM2s, OM2n, OM-G and OM-4T bodies, and a whole bunch of other lenses that I use less frequently.
As far as reliability is concerned, other than a bit of preventative maintenance, my OM lenses and bodies have required a total of one repair in 45 years - a mirror that required re-attachment after the glue failed about 40 years in.
Here is a photo of my OM-2s in 2010, on the occasion of my unloading my very last roll of Kodachrome. It shows just a bit of wear
View attachment 246894