The largest size I can print at home is 16 X 20. I use a 60mm wide angle lens for 2-1/4 negatives, to allow some room for cropping and the trays barely fit in my small darkroom. My archival print washer is 11 X 14, so I use a large tray and a Kodak tray syphon for washing this size. I've printed 20 X 24 in a friend's much larger darkroom, but that's something of an athletic feat, what with handling the large wet paper and reaching up to focus the enlarger and bending down to the focusing scope (I didn't have a WA enlarging lens then, which might have enabled me to focus while viewing the projected negative).
11 X 14 is somewhat easier to print than 16 X 20, but the latter makes more of an impression on the wall. FWIW, the largest pre-cut mats I've been able to find are 20 X 24, with an opening for 16 X 20 prints. That's a major consideration; I'm too klutzy to cut my own mats and custom-cut ones are quite costly.