My two cents:
Sigelei 150W - The 100W and 100W plus boxes have gone a long way in restoring faith in Sigelei as a company. The fact that they have opened up a US service/warranty center is great, should you run into any issues. This is a well-specced box, and while I have not played around much with one, I would expect it to perform well. The price point definitely makes this a contender.
IPV3 - I have seen IPV2's which have been nothing short of abused continue to work like a champ day in and day out. I would not expect any less from the IPV3. It sits a little big in the hand, though - definitely a touchy-feely before buying box for me. It can be a little pricey, though, P4Y was pretty aggressive with their minimum pricing. Is it worth it against the Sigelei, though???
GodBox - no. Just plain no. It's so big, it's like vaping on a dictionary. A 0.5 ohm lower limit (although I have seen instances of them being built down to the high .3's) doesn't make a lot of sense for a box specced like that. A coworker had one, and used it for about a week before she traded it for a Valkyrie which had been dropped in gravel a number of times over. Given what you are looking at, I would just cross the God Mod right off the list.
Hexohm. Hmm, an interesting entry in this list, as I consider the hex-ohm to be a semi-mech. You are losing a lot of the protections offered by the other two reg mods. When it comes to building, you take all the control into your hands, as this is a VV device, as opposed to VW like the others above. The lack of a voltage display (although there are other Raptor and OKL/OKR chipset boxes have voltometers) means you either need to vape by feel, or pack a voltage checker around. It is possible to break through the specs of the chip, though, and the chip will not last long. Recently, we had a member on the local FB group fire a 0.09 ohm coil on his Hexohm. I am just glad it is still working, as anything under 0.3 ohm will just stress the chip. Hexohms and other boxes in that category are very nice, though, but due to the way they operate in general, they are in a different class compared to the other three.