I've just repaired a friend's dreamcast and I think even it's dead and no more new games are coming I'm just having a lot of fun with it (i told the guy i haven't repaired it yet & copied some games) and I'm having a lot of fun with "old" games like virtua tennis, crazy taxy, power stone, dead or alive 2, soul calibur, ferrari f355, resident evil code:veronica & more that are coming ( i just need a master/slave cable to rip rent GD-Roms into CD-R)... DC is just a good choice if u dun wanna waste money (mine is 100% "free") and anyways now its not very xpensive...
If u don't bother the fact that there are no new games coming, 2n hand DC it's the choice(till PS2 prizes go lower)... If not, well PS2 has the wider game selection and, even Xbox still have a lot to offer, it's the best choice... About Gaycube... well, if u like nintendo games, as a console it's OK....