The sigeli will work just fine with the atlantis. Just pay attention to what the resistance level is on the coil and don't exceed it unless you want to burn up the coil. Now I've ran my atlantis on almost every kind of mod, variable power, unregulated/ regulated box, mechanical mods and so on and it works great on everything. Now if you want a nice inexpensive clearomiser in my opinion look into the smok vtc pro, I'm currently running it on my ipv4s and I can fog up a room easily. I have .6 and .2 ohm coils for it and you can run either from 30-80w. Also the ipv4s is a great mod that goes to 120w but can go higher if you update the firmware from pioneer for you's website and has temp control mode if you want to do nickel or titanium coil builds in an rda which is nice.
Now when it comes to cloud chasing, power in a sense is important but there are many factors that go into it, not just getting some super powerful setup and going with it. Cloud chasing is an art form and takes practice. Now an unregulated box mod running 2 18650 batteries is a great start for your mod and you will need a good rda. You don't necessarily need a competition rda but look for one with really good airflow cause airflow is very important. I suggest some of cloud chasers inc rda's cause they are designed for well.....cloud chasing lol. Also the coil build you use, the way it's wicked, the juice you use, I recommend 100% vg, and your technique are all very important. When it comes down to it though it's all by preference and in the end it's your hard earned money buying it all. Anyways that's my input. Have fun with it and enjoy it to its fullest but mostly be safe with it.
