I haven't changed my app usage much over the past few years. When it comes to weather, I really only use RadarScope. Google Chrome is my mobile browser of choice when looking at satellite imagery, mesoanalysis, observations, etc.
RadarScope - always my go-to for radar, with pro subscription
Google Maps - navigation, but also for finding places to eat and rest at (with reviews)
Gas Buddy - great for finding gas in rural areas, as well as the lowest prices
Yelp - helpful with finding restaurants and other attractions, although Google Maps tends to have more reviews in the most rural areas.
Wyndham Rewards - I switched over to this app for booking the majority of my motel/hotel stays. Most accommodations in their chain are reliably clean/comfortable, especially once you do a quick scan of the reviews. Also, their prices are competitive with the app, especially if you travel a lot. I used to predominantly use Expedia, but I find deals that are just as good by becoming a Wyndham Rewards member. With every three stays (3,000 points), I get a discount that's usually good for 20-30% off my next stay.
For some quick photo/image editing tools...
PS Express - quick and easy to touchup photos on the go. When I want to share photos from my phone (which aren't the highest resolution), I can make a few quick edits in this app to get the photos looking sharp.
iWatermark - a great app for watermarking photos via iOS
Aviary - I still go back to this app when I want to draw/annotate on maps, either to share on social media or to send to other chasers.
InstaSize - a quick way to format panoramic photos for sharing on Instagram.