If you’re wanting off-the-shelf and easy to use, pretty much anything DJI is going to let you set up mission plans and execute them. I’m a big advocate for Dronelink; it lets you set up mission plans in the browser, syncs to your phone, then executes them through the controller:
https://www.dronelink.com/The cheapest path here is a used DJI Mavic Mini. It’s not nearly as capable as the current generation stuff, but it’s cheap, and well-supported in Dronelink.
If you want DIY, the choices I know best are iNav and ArduPilot. Both of those are generally run on custom-built UAS, and in my experience any quad you buy like that will end up changing over time with replacement and upgraded components.
I buy my parts at GetFPV and Pyrodrone most often, with RaceDayQuads as an occasional vendor. I’ve had particularly good experiences lately with Pyrodrone. I got a ~$130 charger that failed in the first few hours of use; not only did they issue me a credit almost immediately, they gave me permission to tear down the charger I had to see if I could fix it first. Not many companies out there would do that!
Unfortunately, all of the pre-built stuff I see out there at the moment runs Betaflight. I love Betaflight for what it is, but if you’re interested primarily in mission planning you’re going to be disappointed.
I recommend joining a couple of iNav and ArduPilot Facebook groups and just looking around. There are lots of people who are very knowledgeable there in extremely niche areas. Part of why I can’t just point you to a specific hardware setup is that there are a ton of tradeoffs that have to be taken into account and what is best for you depends on your very specific use case.
For example:
I use my Autel Evo 2 Pro for almost all of my videography stuff. It’s not supported by Dronelink (last I checked they were working on it), but the iOS app’s mission planning is sufficient for about 80% of what I do. I can manually pilot the rest. The E2P has a rated 40m flight time. In reality, I usually get about 28-32m of usable flight, because I’m not interested in trying to stretch the limits and risk my UAS.
If I were wanting to do large-scale orthomosiacs and mapping, I’d go with a custom flying wing. Those can easily get well over an hour of flight time and can carry a substantially larger payload. Mapping imagery is usually taken at “nadir” - straight down - so I could use a significantly simpler gimbaled camera. If my wing was stable enough, I might even be able to get away with no gimbal at all. I’d likely fly it through a separate onboard FPV camera, though I might omit that as well if I were using exclusively planned mission stored and executed onboard. I’d build that myself, and probably start with a body kit like an AR Pro: https://www.getfpv.com/sonicmodell-ar-wing-pro-1000mm-wingsp...
Note that the link above is a “PNP” kit, so technically you could add a receiver and start flying. It doesn’t come with a flight controller, camera(s), gimbal(s), or video transmitter. All of that would have to be added, and a down-facing camera would require modification to the body, gimbaled or not.
At that point, it becomes worthwhile to at least consider building the airframe yourself. There are lots of plans out there, and it’s not _that_ difficult to learn to design them from scratch. Fusion 360 has some F/OSS plugins to help with designing airfoils and calculating all the metrics you need to get it right.
The reason I’d go for a fixed-wing for mapping is twofold: Generally speaking they’re faster in a straight line (mapping missions are generally composed of a bunch of straight lines with turns between them), and they’re far more efficient and easy to get relatively long flight times.
A multirotor is always expending power to fight gravity and stay in the air. That gives it the ability to hover and do all kinds of crazy acrobatics, but it means that there is a point at which adding more batteries expends more power keeping it aloft than you gain from the additional capacity. A fixed-wing stays in the air because of the lift generated by the airfoils, and you only need to keep it moving fast enough to generate sufficient lift.
To give some idea of how that works out in real life: I have a “powered glider” that I fly for fun that uses a 3S 1300mAh battery. It can do mild acrobatics (lazy loops, Immelmann turns, etc.) for about 35 minutes. If I’m just flying level, it’ll fly for around 45-50 minutes. If I’m flying at one of my favorite spots - a small but steep hill with a creek at the bottom - and I’m trying to stay up as long as I can, I actually don’t know if there _is_ a maximum flight time. I’ve gotten up to 2.5 hours before I decided I’d had enough for the day. A light enough aircraft with enough lift, taking advantage of thermals and updrafts, doesn’t really rely on powered flight much.
My “for fun” AR Pro uses a 4S 3500mAh battery. It has ~3.6x more energy available, but I usually only get about 12-15 minutes of flight time. It’s flying a lot faster, though!
My favorite freestyle quadcopter is built on a 5” Armattan Badger frame. On a 6S 1300mAh battery, I get 3-4 minutes of acrobatic flight. At most, if I were only hovering, I might be able to push that to ~6 minutes.
In other words, the quadcopter above flies for All of the above use lithium polymer (“LiPo”) batteries. The care and feeding of those is a topic unto itself, but for the purposes of understanding efficiency, know that they’re rated based on the “per cell” capacity. A 3S battery has three cells, a 6S battery has six cells. Each cell is 4.2V at full charge and ~3.5V when discharged. A 3S 1300mAh battery has half the capacity of a 6S 1300mAh. The 3S outputs up to 12.6V while the 6S outputs up to 25.2V.