Both the ThunderJet Alexis OB Offshore - 21 ft. 2008 and the ThunderJet Landing Craft 2011 are modified-V designs, both built in aluminium, so 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 500 hp, the ThunderJet Alexis OB Offshore - 21 ft. 2008 has a 350-hp advantage over the ThunderJet Landing Craft 2011's 150-hp ceiling - enough to notice on acceleration and at cruising speed, particularly with a full passenger load. Both carry nearly identical fuel loads - 50 gal and 48 gal - so range won't be a tiebreaker here.
Both boats are rated for 6 passengers - a good fit for a family of four or five plus guests. Comfort at capacity is another matter; the longer hull typically means more seat options and better weight distribution.
Bottom line: Performance buyers should lean toward the ThunderJet Alexis OB Offshore - 21 ft. 2008 and its 500-hp ceiling. If fuel economy and quieter running matter more than top-end speed, the ThunderJet Landing Craft 2011 with its 150-hp rating is the more economical daily driver.