Best <10k cycle

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Hi everyone! I'm getting a starter cycle for a friend.  But I'm out of date - what might you recommend in the <10k range? I once had a single speed decathlon MTB (maybe it was 5-6k eight years ago?) And it was a smooth ride and reliable. I'd consider that again.  Geared is good, and I'll gladly pay  a bit more for a better cycle, but I'd rather get a reliable single speed than a janky geared one (gears jumping and chain jamming, requiring continual adjustment).

Thanks for all suggestions!