when you say "making maps" - what exactly do you want to do while in the field? are you just recording waypoints and tracks with notes or ...?
i use an Android tablet with built-in GPS and the
AlpineQuest app. the USGS topo maps provided by the Caltopo map source will give you terrain, mines, wells, old cabins, etc. and you can get cacheable satellite data from the Bing or HERE map sources. of course you can get street maps as well from several sources, but it does not do turn-by-turn navigation. it also has a "land management" layer provided by Caltopo that you can overlay at any opacity and see who is responsible for that area (BLM, NFS, state, etc.). you can use any map source as an overlay and combine several layers even, such as MVUM trails, terrain shading, etc.
you do have to pre-cache any map source you want to use in the field, but it's much easier than with Google Earth. while you have internet, you simply pick your map source, draw a rectangle over the area you want to cache, specify what zoom range to download, and let it rip! the app is fairly generous as to how many map tiles you can download at once (compared to similar apps), and if your area exceeds that amount you can simply run it again and it will pick up where it left off (only downloading the missing tiles).
for map making, you can create waypoints with any icon, name, and description you like and even take a photo with the device and attach it to that waypoint. tracks and routes can be created by drawing directly on the screen, or you can record a track real-time form the GPS input. it can import and export GPX and KML/KMZ, as well as some other formats i think. it's not GIS program though, waypoints and routes/tracks are the extent of the notations you can make. there's no polygon or area type tools, etc.
all of the tablet/phone apps offer similar feature sets (Backcountry Navigator, Orux, Gaia, Locus), but i've found that AlpineQuest has the right mix of intuitive interface and advanced features for myself to prefer it over the others.
also, worth noting, if you're tech-savvy, you can use the open source Java software MOBAC to pre-make map files of very large areas on your desktop computer and avoid having to do the pre-cache routine within the AlpineQuest app. MOBAC can make files for several of the popular Android apps actually.
i'd recommend a 10" tablet since you want to interact with the maps a lot. i use an 8" currently - it fits in the Jeep well and is plenty for basic use. you also want to make sure you get one with a microSD slot and that is modern enough to support at least a 128GB card (which are reasonably priced currently, 256GB are the largest available at this time but pricey).
a challenge with Android tablets can be finding one that has a true GPS chip built in (one that doesn't require network/wifi assistance). nearly any tablet that has cellular data capabilities will have this feature (which can be used even outside of cellular range. it's just that the cellular radio chipsets almost always include the GPS features). however, for WiFi only tablets, avoid the "lite" version of any Samsung tablets as those definitely do not include a fully functional GPS. personally i would only buy from somewhere you can test it and return it if you go with a WiFi only one (FYI, Best Buy will price match Amazon). you want to ensure that an offline map app can achieve a GPS lock even with WiFi and cellular data turned off. the free app
GPS Status & Toolbox can be used to test this (put it in airplane mode then turn on only the location/gps feature then open the app and see if you can get a sattelite lock in decent time).
i've successfully used several different tablets mounted in vehicles over the past few years (Motorola, Sony, LG). they've all had Verizon service though - i'm willing to pay the additional $10/month on my plan to have data around town for things like streaming radio, real-time traffic in Google maps, etc. all of them have worked well in terms of getting a quick GPS lock with simply being mounted on the dash. heavy forest cover or deep canyons will of course make you lose signal intermittently with nearly any device. note that if you get a tablet with Bluetooth, you could use a separate external GPS device which might offer a better antenna/chipset - i've never had the need for this extra complexity.