Part of it depends on your end goal.
Slant back is great if you have a turret install in your future, and have $10-15k to spend now (along with another $5k when you want to do the turret)
Slant back does tend to leak like a sieve though.
You're looking at a day or three to install it all depending on your level of mechanical ability, tools, and how many people doing it.
Helmet Hard Top (amtech hard top) is a LOT less work to install, a lot lighter, and a lot less complicated. The fiberglass is very sturdy (except for those two little strips coming down at the B-pillar). I believe the roof is rated for a 500 lb load.
You're looking at a couple of hours to install it, and the removal is just as quick if you decide you want to go without a top for an event or something. There should be 4 rings on the top to use for lifting it, if you have overhead beams available.
I installed and removed the one on my truck (a mid height version, so 2 feet taller than the one everyone is familiar with) by myself in a couple hours with some ratchet straps, a tree, some 2x4's, rope, a snatch block, and something to pull the rope, in my case a farm tractor, but any vehicle would have worked.
With 4 decently strong guys you can just pick them up and set them in place.
The main thing I dislike about the slant back is the amount of space you lose in comparison to the HHT. That and how much it leaks (I live in Western Washington where it likes to rain most of the year)
Oh, and since the slant back is all steel, you can burn yourself on it if left in the sun too long, and the insulation on the inside will likely need replaced.
The HHT being fiberglass has a lot less heat transfer, and while it gets hot, it isn't the same "instantly burn yourself" type of heat transfer that steel is.