I haven't seen this mentioned yet so I'm going to throw in some info. Almost all tanks have the same connector. Almost all mods have the same connector. It is called a 510. For the most part you can swap any atty out onto any mod, regardless of the manufacturer, as long as it has a 510 connector. Any reputable (and even non reputable) manufacturers will list te type of connector on their hardware. All in all you can pick the hardware you like the best and mix and match. So when you ask for a mod to be able to have a quad coil option, that's like asking for a power drill to have a Philips head option. It is the tank that accepts the coils, not the mod.
I am not a hardware hobbyist (I'm a coil hobbyist) so I don't have personal experience with a lot of it. But here's my 2 cents on mods.
1) Smok Alien - I have had 2 Smok Aliens (first one was from the first batch my local shop got in years ago) I used and abused that thing and it kicked hard up until early 2017 when the 510 connector started to come out of the socket. Within a month after that the fire bar fell off and the top plate screw mounts broke. But, I can still screw an atty into it and it fires up just fine. The second one I purchased shortly after the first one started to fall apart. I've had a small problem with the pin coming off the spring here and there but on the whole it is still working fine a year later. It is still one of the most aesthetically pleasing mods on the market (imho). The screen is a little 8-bit compared to what you can get now. But it gives you all of the info you need and at the very least isn't ugly. It feels great in the hand. It isn't so light you feel like your going to break it, but isn't so heavy to be a rock in your pocket. Of my 4 mods it is still my favorite.
2) Weismec Noisy Cricket-II - This thing is great!! Kind of an all in one option. Regulated (podentiometer), parallel unregulated,series unregulated. It's plain and simple looking but you can get wraps made for it with many different design options. There is no screen. The voltage dial is a little finicky. But it's dirt cheap. And it's a rock solid vape. Got it at my B&M for 25 bucks and seen it online for 15. But be warned, this can be a dangerous mod when not used appropriately.
3) Pulse 80w BF - Not really what your looking for since your looking to tank and not sqonk. But something to look at if you decide to get into RDA's and squonking. It's a great introduction to the style.
4) Smok Majesty - Purchased this as a back-up/beater not long after the second alien purchase. This thing is crap. It has a REALLY hard time pushing the wattage you ask of it. Same build on it vs. the Alien and there's a gigantic difference. And not that long ago the positive board connection just strait broke off. Now that's not a mark against the mod since it could happen to any mod. But it is an indication of the well known horrid Smok QC.
5) I have not owned a Mag but I've heard horror story after horror story about their quality. People having to buy 3 or more in a month. And smok customer service is non existent. Pretty much if a Smok mod breaks you eat it, unless your shop is willing to take it back. So, check in with your supplier about return policies before purchasing.
As far as coils for tanks go ... DO NOT get a smok tank unless you just can't live without it. The tanks themselves are really good. But smoks coils are just .... so .... bad. Well Let's rephrase that. At least 1/2 of the coils are just .... so ... bad ... When you get a good coil it is a fantabulous vape. But, your flipping a coin every time you put a new one in. This is speaking from personal experience. Other than that I don't have any input on sub-ohm prefab tanks as I haven't used many.
As far as batteries go ... if you are unfamiliar with batteries I suggest doing some research. While most regulated mods have a myriad of protection options ... non of them are foolproof. If one goes out and your batteries are not capable of handling the amperage you can literally melt you mod. When looking into batteries DO NOT take the manufacturers, or even the suppliers, word as to what they can handle. Just google the batteries and find a "mooch" post on it. A lot of the info on mooches stuff is like a foriegn language if you don't know about the stuff. But the important part is finding the CDR (continuous drain rate) in amps. DO NOT just look and see "40 amp" on a battery and take it. Those are "pulse" ratings. It does not account for continuous drain on the battery. With a quality regulated mod a single 20 amp (CDR) battery can handle approx ~57 watts of power safely. That multiplies for each battery. The other major thing to watch for in batteries is getting fakes. The fake industry has gotten pretty good at their craft so it's hard to tell the real from the fake. A good safe option is to go to a reputable dealer, Lightning Vapes is always on point, when purchasing batteries.