As I stated in the opening post, the DS is very probably the console I'd say is my all time favourite. I think the library is pretty diverse and contains a lot of interesting IPs and spin-offs that are fairly unique and many of which wouldnt work as well on another platform.
The DS was the first console I bought using money from work, as a teenager - I'd bought consoles before using money I'd recieved in birthday cards etc, but this was the first big one I didn't have to wait for. Although with a fairly limited launch lineup perhaps I could have benefited from that
That said, the mini games in Mario 64 DS, the bundled Metroid Prime First Hunt demo and Project Rub kept me busy for a while as they were all pretty replayable.
I went to a college (for Americans, this would be aged 16-18, prior to unviersity) a good hours bus ride from my home and me and my friends used to play DS on the way there and back, as well as on lunch breaks. Mario Kart DS, Tetris DS and Pokémon Diamond & Pearl were popular choices for multiplayer, with Advance Wars Dual Strike getting a lot of my time too.
After college I went travelling around the world, and the DS came with me then too, for plane and bus journeys. My original DS is falling apart now, but it's been through the UK, Spain, Japan, Thailand, Australia, New Zealand, Fiji, the USA and Canada in it's time so it's had a good run
I picked up a DSi at launch to replace the original as the hinges have broken and it's pretty beat up, and later down the line I picked up a DSi XL. I was quite a fan of DSiWare at the time, and it's not long now before it becomes permanently unavailable when the 3DS eShop goes down next year.
My DS library is one of the biggest I have (only very recently surpassed by Switch as my biggest collection) and there's a whole bunch of hidden gems I want to share in this thread this month. There's still a whole bunch I havent played too, so I'd love to hear other people's recommendations.