Best musical sub under $1k?

I’m looking at subs under $1k. My mains are KEF LS50 Wireless. The room is about 12’x15’ and the KEFs are on a desk. The sub would go under the desk which is fairly open underneath. I’ve been looking at the SVS SB2000, even the SB12 NSD which is available well under $1k at $400, the REL T/7i and the ML Dynamo 700w sub. I don’t want anything physically large so the HSUs are out.

Thanks for any input.