Many years ago I used an Epson 1240U Photo to scan 35mm slides. I found the results just OK.
I bought the Epson V500 in 2010 & scanned about 1500 slides - the results were incredibly good. Depending upon the quality of the scans you're looking for, it can take quite a long time to scan a lot of slides. Experimentation will enable you to find the right balance between quality & time.
I recommend this scanner without reservation.