The classic 4x12 with Celestion G12M Greenback speakers. Warm, woody midrange with controlled top end. The sound of classic rock.
Both Marshall Studio Vintage 1×12 and 2×12 cabs run open-back Greenbacks. Both pair with the SV20H. The 2×12 is twice the cone area, twice the weight, and a different room experience. Here's when it's worth it.
Two Studio-line heads. Two of the most modified Marshall preamp topologies ever shipped. Which 20-watt version belongs on your board, and which one actually sounds like the amp it claims to copy.
Both run real Marshall circuits in 20-watt format, but a JTM45 with KT66s and a 1959 Plexi with EL34s are different amps. Here's which Studio you should buy.