The "ripple" reference is more a potato chip reference, especially if you enjoy Pringles. Consider placing a plate of glass on a surface. If the glass rocks when corners are pressed, don't use that surface to build your printer. Your printer would be constructed in such a manner that it would not rock, but that means that it conforms to the potato chip surface which the glass presented. I just realized that our glass-top range makes a great build surface for that reason. It doesn't have to be level, only flat, as you won't be referencing earth normal during any build (I hope).

I think it's difficult to compare the two printers head-to-head, as one of them is a dual extruder design. This adds features and can add complexity. I've not researched the Tenlog other than to scan the specifications. I've seen very little in the forums regarding problems with the Tenlog, but mostly because I don't travel much to those areas. Most of my experience is with the Prusa in a support mode, which has been pretty darn easy. Even the standard "turn it off and back on" fix has been used once.

The Tenlog has many features to its credit and I expect if that's the printer you get, you'll become proficient with it. I've considered to purchase one myself, just for the direct drive aspect of the extruders. It has a larger bed than the Prusa, although it does not have an auto-level system. On the flip side of that, the glass bed is likely to remain flat/planar making leveling less difficult than beds of other composition. My Sigma has a glass bed and fiddle wheels for leveling, but uses the z-limit switches to determine level status. This means none of the "stick paper under the nozzle" stuff, which can be subjective.

The Tenlog uses rails and bearings for the carriage, promoting stiffness of design, another plus. I've noted that one can purchase (or build) an enclosure for the Tenlog, making it more suitable for ABS and other temperature sensitive filaments. One can build an enclosure for the Prusa, of course.

Of course, the price certainly is a positive for the Tenlog. I suspect I could be as enthusiastic about the Tenlog as I am about the Prusa if I had been involved in building one. If my Sigma dies on me (so far unlikely), Tenlog IDEX would be on the top of my list for a replacement.