The spec sheets list the Malibu Wakesetter 21 XTi 2008 as v25 wake and the Malibu Wakesetter VTX 2012 as modified vee, so check how each hull rides in the conditions you use before you decide.
On paper these two are close siblings in the size department - Malibu Wakesetter 21 XTi 2008 at 21,0 ft versus Malibu Wakesetter VTX 2012 at 20,0 ft. At 3 400 lbs and 3 500 lbs respectively, both sit in a similar weight class - either should pair comfortably with most mid-size SUVs and half-ton trucks, though always confirm your specific tow rating with the motor added.
The power gap is worth calling out. Rated to 400 hp, the Malibu Wakesetter 21 XTi 2008 has a 50-hp advantage over the Malibu Wakesetter VTX 2012's 350-hp ceiling - enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Fuel capacity breaks the other way: the Malibu Wakesetter 21 XTi 2008 carries 46 gallons versus 41 gallons in the Malibu Wakesetter VTX 2012. On a lake day that's negligible, but for coastal cruising or long reservoir runs the extra range matters.
For family outings this is probably the sharpest distinction between the two. The Malibu Wakesetter 21 XTi 2008 is rated for 12 passengers, while the Malibu Wakesetter VTX 2012 caps at 11. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the Malibu Wakesetter 21 XTi 2008 could be the deciding factor.
Bottom line: Choose the Malibu Wakesetter 21 XTi 2008 if your priority is putting more people on the water - it handles 12 passengers and at 21,0 ft it has the deck room to back that rating up comfortably. The Malibu Wakesetter VTX 2012 is the smarter pick if you want a lighter, easier-to-trailer boat rated for 11 that costs less to run day-to-day.