l am getting the feeling that you kind of like your ipad. I use my samsung for about half of your list. I need to step it up I reckon......I use my iPad & iPhone for everything work related, not just a portfolio:
Mental Note - Measuring/Notes/Sizes
Reminders - Shopping list by company
Invoice2go - Quotes/Invoices/Sales
Pages - Fact/info sheets for customers
Numbers - Spreadsheets
Floorplans - As it says
Easybooks - Books & accounts
EasyCert - Electrical certificates
EasyGas - Gas certificates
iZettle - Card Payments
Worldpay - Alternative Card Payments
PayPal - Paypal Payments
Pingit - Pingit Payments
Ant.aligner - Antenna aligner
Photos - Work Portfolio
HP ePrint - Wireless printing
Goodreader - PDF reader
Tapatalk - Forum reader
Viber - I allow customer to contact me over WiFi
Orange Maps - Sat Nav to get to jobs
iTorch - Torch for working in dark areas
Radio - Streaming radio where power isn't an option such as a re-wire
Dulux - Paint matching
Screwfix - Catalogue
Newlec - Catalogue
And so on. Be lost without it now!