I haven't even considered a handheld since my GBA. And the only reason I had that was for Pokemon. I have really never gotten into the handhelds, since I've been computer building and gaming since I was 7. So what was it for you?
I've basically had all the major handhelds except the original Game Boy. Love handheld gaming. I hardly play them on the go though, I just get them for their library of games and unique experiences compared to their console counterparts. Technically the 3DS is my most recent handheld and I love it so far but I'm anxiously awaiting my Vita in February.
my most recent handheld is.. well, my iPhone which seems to do games pretty well. apart from that, my 3DS and while i like it, i'm hoping that there are some better games that come out soon. Super Mario 3D Land looks pretty good right about now. i'm considering getting the Vita, too with Disgaea 3 portable and whatnot. i think i'll wait it out..
I was just playing my 3DS. I love handheld games and the DS is my second favorite system I own, only behind my 360.
I've dug my GBA out of my basement now that I'm back home for xmas and plan on diving back into that Mega-man Battle Network sweetness at some point over the holidays.
I really enjoy handhelds, although lately it seems I only play them outside of the house. I get that that's what they're for, but it's like I'm saving them so I'll have something to play on my eventual (imaginary) roadtrip. I want to finish 3D Land and start playing Minish Cap, but I always divert myself to a home console for some reason.
Oh, and the last one I bought was the 3DS. Before that...more DSs, because apparently I can't take care of clamshell-designed devices.
I owned a PSP 2000 and a DS Lite at one point. Sold them both because I never played them and needed rent/spending money (isn't all money spending money?). To be honest there are times when I miss them - long breaks between classes and lunch breaks at work could be bit more entertaining - but this might be because I don't own any sort of 'smart' phone.
Got my 3DS and am having a blast playing through Minish Cap, though the dungeons seem a little easy so far. I've also owned every Nintendo handheld (released in the US anyway) since the original Gameboy. I really like the fact that there are unique gaming experiences you can only find on a handheld, which is what keeps me coming back.
My last handheld system: Original GameBoy :). I used to bring it to elementary school back in the day to play with my friends, but nowadays I have no real need to have a portable gaming device, really. It just seems like playing one while on the road somewhere would advertise myself as a potential victim to thieves.