ok i am probably going to sound like a dick here, but settling into a 'sweet spot' when there are so many options for wire and different types of coil builds is just a self imposed limitation... i do, however, understand the curiosity and data collection aspect of the question, and when i first started i asked a lot of very similar questions until i came to the point im at now, where i say these things that make me sound like a dick...the circle of life.
for me, these categories are the things that influence all my builds more than anything else. am i building a low or high wattage build? what device will fire it? what atty does it have to fit inside? i vape all over the place in terms of power/devices/atomizers, so i cant just pick a build i like and use it for everything.
Power wattage mode high watts (>50) - the majority of my hardware and builds are in this catergoy
Power wattage mode low watts (=<50) - i have a kayfun 5 and a kf3 mini i dont build under 1 ohm, or run over 30w
Temp control - the hohm wrecker g2 is the only mod i use in tc mode, and tc mode is the only mode i use it in
Mech/hybrid mod - yes. parallel, series, tubes, para-series etc...this is my preferred hardware over regulated mods
Regulated mod - i have two generic regulated mods that i use as beaters when i dont want to risk dropping or otherwise damaging a nice one
Single coil - yup, quite often
Dual or more coils - i only build more than two coils for a laugh or a picture. i havent really found a good quad coil build that i prefer as a daily vape over my regular dual coil builds. its also really hard to make fancier coils like aliens come in at a functional resistance when you start making 4 or more.
1) What materials have you tried so far?
ka1, ss316, n80
2) What is your favourite metal?
i cant personally taste the difference enough to choose one over the other, so my reasons to choose one over the other are entirely based on the build im doing (target resistance, build space, coil mass etc)
3) What is your least favourite metal?
never met a metal i didnt like (aside from metalcore)
4) Do you mix and match on complex builds, if yes why? (If you only use simple then N/A)
yeah i do. you can fine tune your vape a lot when you understand how the different metals work together to effect rampup/cool down/coil mass/resistance etc.
5) What is your favourite coil type?
i prefer the best coil for whatever atty/target resistance/device/juice i am building at the time (this is where i start to sound like a dick again because there is no right answer here). to partially answer you though, i prefer coils like aliens or anything with 'staple' in the name, if they will fit in the atty and come to a resistance the mod can fire safely and effectively (coil mass vs voltage etc etc). the 'minimum' coil i build is a fused clapton though, no matter the hardware or target resistance. fc is the most versatile and functional coil there is imo.
6) What is your favourite inner diameter
i prefer the best inner diameter for whatever atty/target resistance/device i am building at the time. inner diameter is just a way to tweak your coil resistance closer to your target resistance. there is no reason to prefer a specific size. as long as it fits in the atty and comes to your target resistance, inner diameter is just a means to an end.
7) What do you build towards (clouds, flavour, mix)
clouds and flavour have never influenced a build i have done. i will learn a new technique/coil and vape it to see if its cloudier or more flavourful, and categorize them in my head for later reference/preference so i can put them in the right atty...but i dont build for flavour or clouds specifically.
8) When making complex coils what are your favourite gauges
i prefer the best gauge for whatever atty/target resistance/device i am building at the time. the gauge of your core wires will determine your builds resistance. you have to choose the right gauge based on that and nothing else. the gauge of your wraps, however, is something you can experiment with. i prefer the smallest wraps that my skill level will allow me to use for the most part...but on a series mod with all that voltage, it can be better to choose a thicker wrap to help cool things down a little. on a tube or parallel box i like to use the smallest wraps i can because ramp up can be an issue at those voltages...but then skill level comes in and i am about 50/50 on being able to make 40g aliens...so i settle into 38 for that one etc etc etc...
in conclusion, there are too many factors to pick a favorite of anything specifically. there are a few different elements of building that only come from experience. once you have that experience, you will begin to answer these questions like a dick
edit - to include some actual info that people can try out for themselves, here are a couple different builds for specific setups that i think make a good balance between coil mass/available voltage/performance. they are all fused clapton builds because, imo, its the best coil for anyone but the most diehard builders/masochists/thrill seekers out there. you can get it to be any resistance depending on your core gauge, its barely harder than regular clapton to make, but performs much better. after this, things only get much harder and give less results.
on a tube (or other single battery mech like a squonk box) i like a tiny four or five wrap, 2 to 2.5mm 2x28 kanthal fused claptons, with at most 38 n80 or ss outer wrap (i prefer 40 or 42). shoot for target resistance based on battery, probably from .15 to .2 ohms. for single coil/mtl/above ohm i like a 2x32n80/42n80 (or ss) at 3mm 6+ wraps.
on a dual parallel box, you can build a bit lower due to the extra amps, which will pull a bit more wattage, which will compensate for bigger coils. a five to seven wrap, 3 to 3.5mm 26 gauge kanthal fused clapton is pretty good. again, shoot for a resistance your batteries can handle. roughly between .1 and .15.
on unregulated series i like a 2x28 kanthal again, but this time in 3 to 3.5mm and 7-9 wraps, with a thicker outer wrap (34 or 36). shoot for a minimum of about .4 ohms. this coils mass, vs the voltage coming out of these mods makes for a pretty hot and sudden vape. if its too hot, add a wrap or two next time you try it.