I strongly suggest point buying. It's not fun when one character uber-dominates the group. It's also not fun is everything is too easy for you, and the DM doesn't dare make things tougher for fear of killing off everything else. And the DM shouldn't sic' the Terminator (tm) on you unless they're really angry at you, but they may if your stats are just too high.
(The Terminator: a monster, often home brewed, designed to defeat a character or party. If the character in question is a mage with Int 25 and save DCs that never fail, then the creatures has SR 50, incredible saving throws, and immunity to all those "save-or-sit-in-the-corner" spells. Or if the character is a monk, then it has DR x/+5, where x is a number much bigger than the monk can dish out per blow. Etc.)
The amount of points is up to you. I noticed that NPCs in adventures tend to have around 30 points, rather than 25, so I'm going to give all of my PCs a +1 boost to all of their stats.