When two boats share the same hull type — in this case both the ThunderJet Alexis - 21 ft. 2008 and the ThunderJet Denali 2010 are modified vee designs with aluminum construction — the buying decision usually comes down to a handful of practical questions: how many people are you putting on the water, how far do you trailer, and what does your tow vehicle weigh?

The power gap is worth calling out. Rated to 425 hp, the ThunderJet Alexis - 21 ft. 2008 has a 423-hp advantage over the ThunderJet Denali 2010's 2-hp ceiling — enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Both carry nearly identical fuel loads — 5 gal and 5 gal — so range won't be a tiebreaker here.

For family outings this is probably the sharpest distinction between the two. The ThunderJet Alexis - 21 ft. 2008 is rated for 8 passengers, while the ThunderJet Denali 2010 caps at 6. If you're regularly pulling extended family or a group of friends onto the water, the extra seats on the ThunderJet Alexis - 21 ft. 2008 could be the deciding factor.