I don’t have the eyesight issues but I have owned the stomp and hxfx. If you don’t need the amp & cab sims and it’s purely effects then the displays on the hxfx will be easier for you in my opinion, you’ll have more of a sense of what effect is in each block to, the downside is, it’s a bigger unit. The screen in the stomp is clear enough, but I found the hxfx easier to read.
All my opinion of course… other people may have different experiences.