Well, I've spent my time fruitfully binge-watching the Fast & the Furious movies 1-7.
Funny thing; even though director Shaun Lin (director of movies 3-6) is clearly the guy who polished the gem that was hiding within the franchise, I'd argue that his films are the worst in the franchise (at least until movie 7, haven't seen the ones after that).
1 and 2 are fun driving flicks. They're about cars and driving them fast, some hijinxs and friendship stuff. If you like cars and driving them fast, these films really deliver.
Films 3 and 4 are basically inferior versions of those films. (Fast & Furious is still pretty good though, it just feels very redundant and "I've seen this already" after the first two.)
Films 5 and 6 are where the franchise stops being about driving cars and friendship and becomes all about destroying cars and mythbuilding the characters into over the top versions of themselves. The films have good action, but also a lot of what I'd call "dead scenes" which explain the not that interesting details of the characters personal lives and relationships. What makes these scenes a waste of space is that they tend to drag down the pacing of their movies while contributing nothing to the films they're in. They don't affect the actual plot and the don't really add up to proper character arcs. Surprisingly little time is also spent in cars.
Then you get to Furious 7, where director James Wan made just a flat out better version of the previous two films. The action is more entertaining, the jokes are funnier, the characters and their relationships work better and most importantly the whole movie has massively better pacing.
If you're only going to watch one film in the franchise, I'd recommend Furious 7 (with the obvious caveat that there's three more films I haven't seen.)
(If you're into cars and driving you've probably already seen 1 and 2, so there's no point in recommending them
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