critH is crit chance, crtD is crit severity. crtD doesn't seem like it does that much, like it applies its modifier before many of the other damage modifiers are applied, leaving the increased damage of the crits not as high as they proboly should be. i would go for crtH every time over crtD

CrtD = higher critical damage (aka critical severity)
CrtH = higher critical chance (aka critical hit)

I prefer CrtDx3 on my DHCs. It gives me 70% critical severity on top of my 66% critical severity passive.

As for ACC, here are some tests that I have done with fleet mates in the past:
1) We compared a single [acc]x3 and [crth]x3 turret. From what we observed, against my 80% defense, the ACC modifier hit about 80% of the time with 1.5k. The CrtH modifier hit about 60% of the time with 1.6k. This was with about 750+ shots.

2) We compared a single [crtd]x3 DHC. From what we observed, against a fleet mate's ~81% defense, I hit about 80% of the time with ~750 shots.

I currently have all [crtd]x3 DHCs and a turret. I intend to replace the pre-Season 7 Borg turrets with [crth] to increase my chances to get a placate proc from the T4 Romulan reputation passives.

My double rainbow beam of doom is pure awesome (chrono duel beam bank in the lobi store). I mean... Who doesn't love +100 to badassery when its freaking double rainbows of doom!?

Lol in all seriousness, each energy type has its place in specific builds.