The TFv4's quad coils are probably the best you can get for clouds from a standard prebuild coil tank. I don't have a crown so I can't comment on how much but I wouldn't put my money on it being a huge improvement. You'll really want to look at drippers to see a huge improvement. RTAs are nice as well, but remember then you have to get into coil wrapping, which is fun, but depending on how you build it your results will vary dramatically. The Crius with the Velocity deck is the one that looks most interesting to me for that, but I'm quite happy with my TFv4 with the rebuildable coils so I haven't purchased one. Bellow v2 also looks pretty interesting with it's side airflow, not sure if that's better but certainly interesting.
As for the TFv4 and it's quad coils, huge clouds for sure, but their quite airy, which to me is a turnoff, I prefer a thicker vapor, and clouds be damned as long as I'm satisfied.
Basically if you want more than the Crown, TFv4, Herekles or any of these top tanks offer you're going to have to start doing some coil stuff yourself. Even if you buy the coils premade you still have to mount them and wick them. It's a jump worth mentioning and considering, I as many find it very fun and have made a hobby of it, but it's not for everyone, so consider it and if you want to do it.
Myself I saw the Haze Drip Tank and instantly thought I had to have it, so I have one of those on the way, hybrid between a drip and a tank in a way I've seen no other do (tank below the coils). When I saw the Rip Trippers guy just hold the power down for a good 10+seconds and it continue to just throw out vapor, well that's worth checking out. I of course bought a ripoff (err clone?) to check it out, if I like it enough and the clone isn't up to snuff I'll probably buy the authentic.
One last thing, if clouds are your goal DO NOT get the TFV4 mini, it can't handle the high wattage needed for maximizing cloud production, it just heats up far too fast. It's excellent at 80w or so and below, but once you break 100w you're going to get burnt, literally.