Its kind of a trap, once you get unlimited data and high speeds you start to take it for granted. Nothing is good enough anymore. But when you get abroad on holiday you learn how the rest of the world lives and know that you should be grateful.
One plan? Or Simple Choice.
I've had no problem pulling ISO's down in the evening to my phone (like 15GB overnight) on SC unlimited with tmo. It's not something I make a habit of but I've found out deprioritization only really affects me in a few busy places in manhattan and around international airports. (and this only kicks in after 50GB of usage or so in a month which is not typical)
I get great speeds in the UK, I get mediocre speeds in the EU, I get terrible speeds in the USA. All with the same handset and (SIM) carrier.
In an ideal world I wouldn't have to worry about bandwidth or transfer caps, but I mention this to provide my experience that for me 3mbps is plenty. Some people might need more, but I think that once you get up above 20-30mbps, most people wouldn't notice or care about the difference.