For me the acoustic choice is much easier than the electric; I'd get a Martin D28. It is just a great guitar and you would rarely (if ever) feel the need for something else.
The electric is tricky. Do I want a Strat or LP or Tele? On any given day the answer is different and so I guess I'd have a dilemma. If pressed to make a choice I'd probably pick something like an R8 or R9 (I currently have a '13 LP Traditional and it would work too but if I was going to have only one electric, I think I would upgrade to a Historic LP)
Dreamy option would be a '58 Gibson flying v or a pre cbs Fender strat for an electric and nice pre war martin 000-28 for acoustic.
The more down to earth ,but still expensive ,option would be a Gibson korina flying V reissue of some sort and a Gibson j200 with kluson tuners mind you.
The cheap workhorse option would be a nice Gibson flying V '67 ri ,like the one i got, or a light and resonant Fender roadworn strat with upgrades, lighter than the one i got and a Martin d28 for acoustic,again like the one i got.
So since i got those , i guess i can only dream for the rest more ideal choices of mine.
Why not split the difference and get a really nice hollowbody? I've owned acoustic/electrics before and they always retain an acoustic guitar feel and just happen to have the ability to plug into an amp. A hollowbody feels like an electric but just happens to have the ability to do that acoustic thing unplugged. It always feels like an electric and never an acoustic. Kinda hard to describe until you have one.
And since owning a hollowbody I find the urge to buy an acoustic occurs less and less.
Sure a regular acoustic will sound richer but I'm fine with the tradeoff.
I'm already there. Collings CJ for the acoustic and Fender 50s Classic Player Strat for the electric. I play more acoustic than electric by far, but after years of trying different electrics I decided a Strat was all I really needed for the little bit I do play electric.
I only have one acoustic and it's the only one I need: Takamine F370SS. Solid spruce top, solid koa back/sides, beautiful inlays, gorgeous tone.
Electric... that's hard. I think if I were only allowed one electric at a time, I'd be trapped in an endless cycle of buying a Strat, playing it for a few years until I got sick of the Strat sound, then selling it for a Gibson, playing that for a few years until I got sick of it, then buying a Strat again... If I could have two electrics, they'd probably be a Strat and a Les Paul, but I'd hate to have to give up the others.
Tough choices. I would go for a Martin D 18 and a strat. That's tough because I own a really nice 335 and while the 335 is an awesome guitar, I would get more mileage out of my strat. The acoustic is easy, the hog n spruce combined with the scalloped bracing would allow me to use it for rhythm or lead work.
I currently own only one acoustic - a custom sitka/mahogany OM style John David Scott (a small custom lutherie in British Columbia); and though I'd like to also have an acoustic 12 string and maybe a dreadnaught someday, I could live with just the JDS happily and be quite content. Like others, I'd have a harder time picking just one electric. Since I really like the sound of humbuckers at times, and equally like single coils at other times, I guess if pressed I'd have to have some kind of SuperStrat.
I have 2x acoustics, a '91 Martin D16H and a (c.?....recent) Seagull Entourage Rustic Cutaway.
The Seagull cost +/-15% of the Martin (pawn shop special), but I prefer it by miles!
I played a wedding yesterday and used the Seagull because it has great tone, plays effortlessly, and has perfect intonation all the way up the fretboard.
So, my one acoustic would be the Seagull.
For electric, I could live with just my Squier VM Jazzmaster.
Does everything I want an electric to do, the JM pups are my favorites, the neck has the perfect profile.....feels like a guitar costing 10x the $200 I paid for it.
So a Seagull and VMJM (I paid less than $500 for both!)....I never would have thunk'it!