In the consumer realm, IMO there is not a better scanner FOR 35MM FILM than the Nikon Coolscan V/5000.
The V and 5000 are at their root the same scanner-about the only key difference I'm aware of is that the 5000 can scan an entire uncut roll while the V is limited to a 6 strip negative.
These scanners max at 4000x4000 dpi, which will grain(or dye cloud) resolve films like Ektar 100 or Provia 100F. These are the finest grained films ever made in their respective categories(color print and color slide). For normal consumer print film or anything in the 400 ASA range, that resolution is overkill.
Due to the design of the negative carrier, film flatness is superb(an important consideration). In addition, if you use infrared dust removal(don't use it on real B&W or Kodachrome, but it works great on color print film and Ektachrome-type slide film) it collects the IR data in the same pass as the scan so actually works fairly fast. The lighting is all LED, which has the advantage of minimal color drift over time(most other scanners use fluorescent lighting).
As shipped, the scanner would have come with a slide holder, a strip film feeder, and a negative carrier that fits in the slide holder to hold 1 or 2 unmounted frames. These parts can be expensive to buy individually, so I'd advise looking for a scanner that includes all. I actually don't have the single frame holder. There are a few other odds and ends available-I've seen a slide feeder, for example.
Nikon has never known how to write good Mac software, and the Coolscan software is no exception. The most recent version is carbonized, meaning it will run both in Mac OS 9 and OS X. It is a PowerPC only program, meaning that it will not run on any operating system newer than Snow Leopard(10.6). It's also a bit clunky, but admittedly is a good piece of software even if not overly intuitive(and I've been scanning film for 10 years). I don't know what the recent Windows compatibility is like, but a dedicated XP box would probably be a safe choice.
Fortunately, the Coolscan V is USB(2.0) so you don't have to worry about Firewire dongles if using a newer Mac, getting Firewire to work at all if you are using Windows, or getting SCSI to work on either platform(my dual 2.7 G5 has SCSI working in Leopard, but it was an absolute nightmare to get there-G4 and older computers and older versions of OS X are a lot easier)
Vuescan is a great 3rd party program that will run almost every scanner on the market and is kept up to date. That means that it works perfectly in High Sierra. Unfortunately, its one major failing is that it doesn't have digital ICE. ICE is BOTH the scanner hardware(IR channel scanning) and the algorithms that make it work. Vuescan can use the IR channel scanning, but their algorithms aren't as good as the ones used for ICE. I've made side-by-side scans and ICE does a better job both of cleaning and of retaining detail.
With that said, a flatbed is a much more flexible option. Epsons are pretty well the gold standard in the consumer realm. I've been very happy with my V700 aside from the terrible medium format film holders(there are 3rd party ones that are supposed to be better). I opted for the V700 specifically because it can scan 4x5(immediate need at the time) and 8x10(possible future need). It can handle 2 strips of medium format, 4 strips(6 frames each) of 35mm, or 12 mounted slides. The V750(and V850) come with a glass mounting tray that can also be purchased separately for use on the V700 or V800. I mostly use mine to wet-mount medium format and large format when I want the best quality scan(again, the MF holders are terrible) but it can also be used-wet or dry-if you have other formats like 110, 126, or 127. Unless you need to scan large format, the V600 is a lot less expensive and will handle 2 strips of 35mm, a single strip of 120, or 4 mounted slides. Optically, the Epsons aren't as good as a dedicated film scanner, but they're more than acceptable for many uses. They are also slower than the Nikon when using ICE or equivalent as they have to make a separate IR channel pass.
I THINK there is an Intel-native version of Epson Scan that will work with 35mm, but haven't actually used it. Epson Scan also has real ICE. Vuescan will run the Epson scanners as well.
