What is the best batch photo resizer app?

For years I have used Shrink-o-Matic, but for some reason it won't load onto my brand new iMac. Is there a good batch photo resizer out there? What I liked about Shrink-o-Matic was that I could put in the parameters of, say, 1000 pixels width and 1000 pixels height, and it would choose the larger of the two dimensions and reduce the photo accordingly, and in proportion. Example: if half the photos in the batch were in landscape mode, and half were in portrait mode, it would reduce the landscape photos to 1000 pixels width, and the appropriate proportion of height pixels, rather than distorting the photo by making both width and height 1000 pixels. When I tried using Preview to batch resize, I could only do all the portrait sized pics in one batch, and the landscape sized pics in a separate batch. Just FYI, I do not use Photoshop or Lightroom for editing, so those aren't options. Can anybody help? Also, info below is wrong. I'm on a brand new iMac, Retina 4K, 2019. macOS Catalina version 10.15.2. Thank you!