Pretty basic, but what I use on my iPhone 6...
Aviary (fun app I like to use to draw on images)
Expedia (find and book hotels, great discounts for members)
Google Maps (GPS)
iWatermark (watermark photos on the fly)
PlayMemories Mobile (viewfinder and remote for my Sony Action Cams)
PS Express (to quickly touch-up photos)
RadarScope
Voice Dream (text-to-speech, great for listening to AFDs, MDs, etc.)
Waze (backup GPS...will read voice in background, unlike recent Google Maps update)
Yelp (find great restaurants, check hotel reviews, etc.)
Underlined apps are ones that I find especially helpful while storm chasing.
iWatermark was fairly inexpensive, $1 I believe.
Voice Dream was about $10, but definitely worth to purchase.