Anti-protons are good (I suppose) from a pure dmg standpoint, with their greater than normal +crit damage. They tend to be about the same in +crit chance as other gear their level, but the main consideration is the skill point investment. Compared to say, buffing phaser skill, buffing your anti-proton skill is a serious point investment, meaning you've got less to throw in other stuff, like weapon performance, or ship-class skill, etc.
thats not a shield bypass, ive done it many times, crit overload 3 with ap dual banks and full decloak/attack buffs and you can crit 50-60k, if hes running rsp and no resists, it burns the shield, scorches the hull, and then the shield heals, still get anything > then the shield facing through to hull with rsp running, its the bleedthrough from hell when i crit
I like the anti protons for my cruiser and disruptors for my escort but all of the beams are good and the differences are not great enough to make anyone of them so much worse as to make you weaker then your foe's.
A nice thing about some of the less used damage types is people are less likely to have shielding against them.