HI Brasilgringo. I've played Water Blast extensively on Defender and Sentinel, but not on Blaster. That said, comparing them across ATs, I'd say Beam Rifle has stronger ST than Water.
Cutting Beam is a decent fairly wide cone. I like it even better with some +range from set bonuses and enhancers. I have it with -Res proc as well, to help with team damage. I use it constantly, it us up often and plays nicely with being ranged.
Piercing Beam hits very hard. its the narrow 5 degree cone. In large groups with full teams, you are guaranteed to hit 2-3 at least until the mobs spread out. I was dubious about it, but I took it and would not respec out of it. It also has a nifty -Res, so even good on hard Single Targets.
Overcharge is the nuke all ranged characters love. Good range, hits hard, big enough area and comes with a nice stun. Also has -Def so you could slot more -Resist IOs, but I use mine for the ranged bonus with 6 slots to soft cap.
Beam (rightfully so) is not an AOE king, it is mostly 'meh'. But with single target at level 51 i'm getting over 900 points of damage with my snipe. I could probably get higher. To me that's good. /shrug. Certainly when I'm taking down Bosses and EBs I seem to do so very quickly. The -Regeneration in Disintigrate is also helpful.
Disintegrate is supposed to add to AoE but its random and I just count it as 'extra' gravy on top of the set. I see the single target energy dots more than i see the disintegate spreading, but I enjoy when it does happen.
Devices adds nicely to the AOE through Caltrops (to a lesser extent) and Trip Mine (all the time). Trip Mine is big damage and I toe bomb frequently to up my AOE and I never feel lacking as a result. This plays well with either diving into a new group of enemies first to lay it down, or by letting pet AI have the mobs come to you for a nice explosive greeting when they try to pummel you in melee.
Beam has become one of my favorite blast sets, not just on Sentinels and Defenders, but now on Blasters, where it shines, even without the Sent chain-AOE.