you just touched the tip of the dick with that magic bro. You control an element with a wide variety of potential forms. Like just choose ice magic, which is water anyway, and you can have weapons for hunting and water and depending on the level of magic you can use you can just change the very damn climate you are in to one that lets you sustain your contructions for long periods of time. That and earth is the best ones to have, fire can be made easily as long as you know what to do so it's not too important. But earth and Water(ice) are just too useful in any one of these climates. Hm, well, ice magic is water magic really but i wonder if you can control both forms or just one? Would suck to just have water magic since ice is a part of it anyway.
Wow this is hard to decide >.<" Hmm chose the temperate forest; it'd be nice to have trees for shade (and maybe fruit to eat) but not too hot or cold or dry, since I'm rather terrible with extreme weather conditions // I'm such a baby ;u; And I'd probably choose water just in case the forest has no water to drink? >.<" If there was water, then I'd choose fire, since cooked meals are rather nice.
Theoretically if you can create a high pressure stream of water, you could carve yourself a cave and tools like a cultivator. But what if water school of magic means that you can create ice too? So Ice\Water magic is the same and it's awesome for survival. Though it would all depend on the way you can use magic as it can be a gamechanger.
I know the usefulness of water magic. Ice magic is another form of water magic, so yeah. I know the full extent of what I get, reason why I chose water. What I said above.
That's a bit pointless to say without making magic system of that world. As basic mastery can mean that you just have a smaller pool of mana and can control only a relatively small amount of chosen element. So no to destruction of mountains and continents but yes to all kinds of basic physical(no healing or golems) phenomena on a small scale.
There are a lot of biomes that aren't on your list. Subterranean would probably be my preference, like a massive cave system, preferably near the ocean. Although visibility would be a problem, and none of the magics you listed would be suitable for that. The only one that provides light is fire, and that would be problematic in a confined underground space. Chances are, I'd take fire magic and just not use it on a large scale most of the time, relying on things other than magic to deal with the magic beasts if possible. If I have some other solution to the light problem (maybe there are luminescent plants or crystals available, or I have access to artificial lighting), I'd go with earth magic to take advantage of the environment. Temperate swamp/wetlands would be nice too, and I'd have to go with water magic there. Really though, being stuck in any single biome for an extended period of time would be a problem.
Depending on your amount of power and control, any element can be used for survival and op skills. If all you have is a basic level of skill, but a bottomless supply of energy, for instance, or at least the time to to keep working at low level. Fire: a tinder burning lighter sized flame, can be used for carving wood, starting your campfire, and therefore creating a shelter for you and containers for your supplies. Water: a drop or so of water a minute is all you need for survival, and for similar construction uses as the fire above, set the drip going over a rocky outcropping and eventually you will have stalactites over your trough of crack rocks, carefully drain the moisture from your packed mud constructions for a more solid build, and other such things. Of course using a branch to drill a hole in a rock and then freezing the inside will crack your rocks faster, but you work with what you have. Air: if you don't have windcutters, then even gentle breezes will drop loose, dry, branches and fruit. if you are generating the air, then you can use it for underwater fishing, or underground exploration. carve some rocks and twigs to make an air powered chainsaw (relatively slow speed, but at least it's not musclepowered). Earth: easiest one, raise and lower the ground, maybe condense soil back into rock, and you can knock trees over (move soil to displace and lift out roots) onto your sharpened rocks to build your home, pack the gaps with raw earth. Edit: Anyway, these were lowest level examples I could think of with each, not where I think "basic level" would be.
I would choose temperate grassland, more ways to look for food, and It's easy to dig your way into hiding with earth magic, or find things with earth magic that you could use like metal which you could use to make crude versions of tools. you could also find water with earthmagic by digging a hole to the aquifer that most likely lays below the land.
Towards Air and earth you went more biased. Water you can make only one drop in a minute but you can generate air to shake trees and make a freaking chainsaw and air pockets underwater? Earth: To lower and raise the ground?? To knock trees over?! You should either set basic abilities on the level of fire with similar control, or on the level of air\earth. Because as you have said, depending on the amount of mana you can do almost everything you want with any magic. Except fire. It's more destruction than creation oriented.
That chainsaw is basically just a stone and wood pinwheel, like a water wheel or windmill, you can set it up next to a tree to have it hack away, gentle breeze is still the only thing moving it, just depends on where you are applying the breeze. What were you imagining when I said moving earth around? A shovel full of soil at a time is enough to knock over a tree the way I described. Edit: sorry i'm not as knowledgeable about fire, but if movies are correct, it can make water, manipulate wind, and cause things to expand.
Fire is obviously the best choice here. Most animals are afraid of fire and magic beasts wouldn't be any different. Even if you burn a magic beast to death with fire magic, not all of the meat would be charred. So, your meals are instantly resolved. Water isn't really any issue either unless I am in the desert biome. Besides, once civilizations start popping up, you could easily set up yourself up as a god by showing them some flashy fire magic.
Temperate grassland,with fire as my element. I pick grassland because forest have too many bugs,and I hate bugs,but ai don't want to be too hot and dry so temperate grassland it is