I like both MPPP and NXT. I never tried #20. They all seem like quality stuff, though, nothing you'd feel like you wasted your money on. MPPP looks very nice and is a good balance of gloss, depth, and shine. It has a very nice well-rounded look that isn't amazing in any one area. It is smooth-slick, but doesn't bead water that well. There are a few reviews in the "reviews" section up top there.
NXT is very easy to find, easy to use, low cost, and very glossy. It's hard to imagine anyone arguing with those aspects. I think it looks very nice with good depth and shine, and simply amazing gloss. It also feels very slick. Durability seems to be different for different people, but I've certainly found it adequate, and it's easy to apply so it's not hard to toss a coat on every month or so. For something you can walk into any Wal-Mart or Target and buy, it's simply amazing.
Of course, none are miracle products, and you need good prep first. If you want a more cleaner/wax sealant product, ColorX sounds pretty intriguing. I have a bottle to try but haven't gotten around to it yet. It is also easy to find locally.
:wavey