Meguiars is good stuff, I recommend it. There are a number of different types of waxes out on the market, but mainly fall into two categories: Carnauba and synthetics. There are also a mix of the two (which I prefer) that give predictably mixed results. Carnauba generally gives you a nice DEEP shine, makes the paint glow with depth and clarity but tends not to last as long, especially in the summer. IIRC the melting point of carnauba wax is 180*F, which, on the surface of a dark car in the summer sun, can be achievable. It also wears off much more quickly, so reapplying is necessary more often. Synthetics don't give as much of a deep shine (though some claim to) but usually last much much longer on the surface and do not need to be reapplied every few weeks. Synthetics also have a higher tolerance for surface heat when applied so if you can't find a cloudy 70* day it os okay, and some will allow you to wax the whole car before you start buffing. NXT is a synthetic IIRC, sounds like it fits your requirements

I use a synthetic-carnuba mix, which is sort of in the middle of longevity and appearance.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth