I'd probably recommend the Model: Samples if you're interested in sampling, or the Novation Circuit if you want to focus on synthesis. The Model: Samples in particular is great - it's an adaptation of Elektron's more expensive Digitakt that puts the core featureset in a more focused box. It would probably be my sub-$400 desert-island groovebox choice.

Edit: it's worth noting that both of these systems are sequencers, not tape recorders. I consider that a benefit (much longer record times) but if you want a multitrack recorder then you should look elsewhere (maybe a 4iXo DAC?)