Imo you'll always get multiple answers on filtration. It's all about preference and how you set them up. Contrary to what most people think it's not all about water turnover, media type and setup are big factors, media volume by water turnover are another. People also oversimplify water changes-- not going to try and explain it all here, but the short version is most people remove nitrates through water changes, I like big water changes myself, but you can set up filters/media to support the anaerobic bacteria that remove nitrates, what some people call a "complete cycle" with nitrogen gas as the final product vs a "partial cycle" with nitrates as the final product-- the only thing about it is setting up a filter that way takes a lot of, and the right kind of, bio-media, not cheap and not something most people think much about-- and the nitrate removing part of the cycle takes months instead of weeks to achieve. A lower tech option is plants for removing nitrates, then there's algae scrubbers, etc.
My point is most people are pretty conventional with filters and maintenance, but there's more than one way, from simple and conventional to more sophisticated.
The Seachem Tidal filters are a well thought out design and seem to be well made, I have one (Tidal 110), my only filter right now that's not a canister. If I'd discovered the Tidals sooner I might have more of them by now. The 110 Tidal is intended to rival the Aquaclear 110, I believe, don't know how it compares in total media or real tank capacity, but they have an advantage over the Aquaclear in priming with the submersed motor, none of the issues with restarting after a power outage. I know, a lot of verbiage most people won't care about, but I only say it all because most people aren't familiar with the Tidals or
options for setting them up.
Imo you could easily do Tidal filters on a 120, three, possibly two, depending on how heavily stocked, how you set up and maintain the tank and filters, etc. But there are plenty of options according to budget and preference, like one good sized canister, a medium canister and a Tidal, all Tidals, etc. I've run a fast, small filter or a bigger, slower filter on the same size tank with similar results, aside from the smaller filter needing more frequent maintenance and the fact that a larger filter set up properly will reduce nitrates.