All maps have a potential, but some have obviously a poor design, while others are easily runied by too many players, spam, fps lags, etc.
And you can't compare maps used successfully in competitions with maps made just for the looks/design without paying attention to the gameplay (aka pub maps).
I think goldrush is nice under almost all conditions, marrakech too, but it's too big if there are too many players, while on goldrush you can even play 3vs3 and have fun (especially if you play for objectives)
radar is cool but is ruined by r_drawfoliage 1 in all mods without forcecvar (jaymod...)
I like supply as well, but not when there's too many players, especially in the 1st stage it makes no sense you can't even leave your spawn at axis without being pushed by someone.
Delivery is nice too, but with too many players it's spammy, I think it is nice only if you play in a team
Actually et was made for medium/small maps and few players, then they started making ultrabig maps and adding stupid things (double jump) to make big maps enjoyable
so I say goldrush/marrakech are the best for me