(still testing, because I switched from iPhone, most apps are new for me ..)
Launcher: Apex (with Holee Style and icons in 6 rows and 10 columns) (v3.3.3, I read too much too bad things in the playstore reviews for the new v4)
Web: Firefox (see my other topic)
Mail: don't really like any yet, but I don't need it that much anyway. Maybe I'd prefer a Linux-Thunderbird-Port with full-featured menu bar like Thunderbird within AndroPorts (or AndrOpenOffice), however I don't like the fact that you cannot touch in Androports and only use the touchscreen just as a track pad. In the meantime I'm trying hard to like k-9. At least it has a "vintage" (though not customizable) table-view with from/subject/date.
Calendar: after Apple "destroyed" the calendar for me on the iPhone some years ago, I stopped using private calendars, I don't have that much appointments anyway. At work I use Outlook (2010). So maybe if Planet fixes some of the problems with Agenda, I'll be using a private calender again, we'll see. I really liked the Agenda on my Series 3 & 3a, but during school I had more use for a calendar.
File manager: tried various (dual-pane is a must), at the moment I mostly use Ghost Commander, but also mc within Termux. On my Win7 desktop PCs I just use Windows Explorer, on my Win8/XP-Notebooks I prefer the good old "Salamander". I think there is still a lack of keyboard-friendly and desktop-feature-rich Android-Apps, not only in this category. That's why I try using mc in termux, but to be honest, I never really liked those ugly file commanders in DOS, I grew up with Directory Opus on Amiga, even started to program a version in OPL on my Series 3a in the mid 90s - but never finished.(**)
Spreadsheet: undecided yet, have still to play more with AndrOpen Office and MS Excel. If both fail, I'll still have Office 97 via Win98 emulated as a backup option.
Music: not needed (I have my old iPod Nanos for music and I won't change that, I hope my old itunes-version on my iMac with OSX 10.6.8 will serve me the rest of my life, because everything gone worse nowadays and there is no sign of hope on the horizont that anything will ever be as good as before. But don't call me a dinosaur yet, because then how would you call me in 20 years? ;) )
Calculator: I cannot look at that ugly flat stock Android Calculator, so I installed "HiPER Calc".
Text-Editor: undecided yet, playing around with Jota+ and Quickedit. (I think no editor on Android is as good as for example Notepad++ on Windows. Fast file edits are good enough in file managers, but in a stand-alone App I want at least to have tabs, for example.)
**) BTW, I think I sold my Series 3a for the Nokia Communicator in 1996, so that was my first mobile phone and my first smart phone. On the one hand I was really sad that I couldn't write Basic/OPL - programs anymore, but the online-part was more important. What only if Psion had released a Series 3 successor with mobile phone in 1996 instead of Nokia! I even connected the Communicator to my Windows 95 running IBM PC 110 Palmtop ( if anyone remembers this device, I wrote that comprehensive english FAQ between 1996-98. Ah that fun in those good old days. I must admit that this switch to Gemini and Android is a bit of a revival of those old times for me, but instead of hindered by technology and hardware, hindered by software and security restrictions nowadays).
