I have 8 strung up and ready to go, but I tend to play 3 90% of the time. An '63 P, a SUB 4 with an SGD Lutherie preamp, and a Tobias Renegade 4 converted to 8 and covered in trolls.
* I tend to just play one bass, I don't swap them around for tonal reasons. When I pick one up to play I rarely switch.
I have a bunch and play mine according to the music and situation. The SX tend to show up more at dive bar gigs although the Alembic actually has seen some dive bar time. For a long time my semihollow body Carvin AC50 was a "main" bass and then it switched to my Modulus 6er being a main with the other 6ers in the mix too. Currently my main basses are my three G&L L2500. It just depends. About the only one that hasn't been a main axe has been my 8 string (doubled). It's just too specialized to be a main axe in my opinion. But I still DO love what it can do when it fits.
So if you want an old school sound and a Fender headstock shape, I dig out the Jazz or P/J. If I want more agression I grab the G&Ls, if I want more solo range, I grab a 6er, If I want even MORE solo range and non-muddy chords I grab a 7 string, If I want uprightish, AGB kind of sound it's the Piezo Carvin Semi-hollow, if I want classic modern it's one of the Ibbys, And if I don't want to be paranoid about theft or destruction I grab one of my nice SX basses. And within this range of tone there is the fretless-fretted choice as well. As you can see there is very wide range of bass here and if you just picked one of them as a "main" it really would not cover that range very well compared to the whole herd. For example if you really want an 8 string sound only an 8 string bass will do. (though people do tell me they can get by with a pedal instead...personally I'm sceptical)