I'm using an Epson V500, have gone through about 8000 BW negatives, 12,000 color transparencies, 6000 color negatives. Still working my way through my photo libraries, about three years now with the Epson.
Started 10 years earlier with a Microtek that would handle only one transparent item at a time, then an HP all-in-one (C7180) that supposedly matched the Epson for resolution, but was extremely slow and the scanning software didn't work well.
If I was to start with something else, it would be the Epson V600, because the Digital ICE feature on that one works both sides of transparent media (otherwise the performance specs are the same). I think V550 replaces V500, not sure of the feature set. V500-550-600 are in the $200 range, and when I bought, included a license for Photoshop Elements, about $50 value.
Next step up is a big one. V800 lists over $700, V850 is $950. Both can do a lot more with difficult source materal, but even my V500 has pulled images from Kodachromes too dense to project (my wife's, if they had been mine they would have been thrown away) and BW negatives so thin that I never could have printed them.
I'm doing all this work on a Mac. I'm using Lightroom, however, rather than Photoshop Elements, on that platform.
Scanning small format stuff on a flatbed is tedious. I can work at it 2-3 weeks at a time, maybe get through 120-160 slides in 10-12 hours on a good day, 40-80 when the material is being difficult and low humidity is hampering dust control. My stuff is 1/2 frame and full frame 35mm, 126, 4x6 and 6x6 cm on 120/620 film and even done a little bit of 110 (a real pain to work with). My target has been around 6 MP, which means 3200 dpi from 1/2 frame, 2400 dpi from 35mm full frame or 126. Most high volume, low cost scanning services target a lower resolution (as low as 600 dpi), but you can get just about anything you are willing to pay for, e.g. 4000 dpi for about $1 per image, automated scans. Adjust the process for each image, as I am doing at home, at least 10x that from the specialty labs that work for pros still shooting film.
If all you have to work with is 35 mm material, you'll likely be more productive with a GOOD slide/film scanner. PlusTek and Pacific Image in the middle price range ($300-500), Pacific Image at the high end ($1000-2000 range) Models include a batch scanner for 35mm slides, and models for 120 format. Top of line for film scanning, quality and speed, are Flextight from Hasselblad (a little over $20,000 for the X5 model).
Don't consider those $30-50 slide scanners using a webcam to take a picture of the slide. I've struggled trying to get them to work for friends who bought them, they don't work, not even at the online-image level of expectations.