Not much to add, but I've got a pair of 150's that I use for dripping and they've been rock solid since I've owned them (7 months and 6 months) with daily usage. I've also got a 75 that works great, but I typically use my d2 or koopor mini over it.
One 150 has a slightly strange click in the fire button, but has never given me any problems, and same complaints as above on the 75, the side panels rattle a little, but has never caused any issues.
I've definitely been pleased with my sigelei products and am contemplating a fuchai, which I have no need for but it looks cool
If I had any real use for a 50 watt max box I'd definitely grab a vr2 as I've been seeing some Really cheap prices on them (under $30).