For me, I think the 20T HF press is basically the minimal acceptable press for shop work on full size 4x4 type stuff. Sure, you can get by with less, you can get by with nothing, but if you want a press, then I think that's a good base line. I had one for years and it generally served my needs well. First off, anything from a bottom-feeder like HF I derate by close to half. So for reference, if they call it 20T, I figure it as a 10T.
Also, fit and finish is about what you expect from HF. The slide is loose and wobbly, so take some time to shim it a bit; basically add some "gibs". You do NOT want that thing shifting and breaking/spitting out a part with 10T of pressure applied! Second, get real steel plates instead of the cast iron crap plates. Under high localized loads they will shatter, see "shifting with 10T of pressure". I had 1" steel plates I used most of the time. And one final convenience point was adding an air-over cylinder to avoid the hassle of pumping. Oh, and some 3" channel to replace the spindly leg-things with casters to allow easy moving. Also check all welds with a critical eye. Mine was fine, but I saw another that had scary undercut.