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The JL-F50 is the better turntable. It’s a later model, and has a few improvements such as a better design tonearm and fully automatic operation (VL-5 semi-auto), weighs more and has better specifications. The VL-5 was the entry-level model in JVC’s range in the early-70’s, so while it was competent, it was built to a price. The JL-F50 was more a mid-range model.
Here are some of the specifications of both:
Model Introduction Year: VL-5 1972, JL-F50 1977 (winner JL-F50)
Drive system: VL-5 belt drive, JL-F50 direct drive
Automatic features: VL-5 semi-automatic, JL-F50 fully auto (winner JL-F50)
Wow and flutter: VL-5 0.1% WRMS, JL-F50 0.03% (winner JL-F50)
Speed control: VL-5 fixed, JL-F50 user adjustable ±2.5% (winner JL-F50)
Anti-skating: VL-5 pre-set for tracking forces between 1.5 and 2g, JL-F50 user adjustable from 0-3g (winner JL-F50)
Weight: VL-5 7.2kg, JL-F50 9kg (winner JL-F50)
Feet: VL-5 non-adjustable, JL-F50 height adjustable for levelling turntable (winner JL-F50)
You can see that the JL-F50 is better in most areas.
I’m not a great fan of the weighted bar and lever anti-skating system on the VL-5. I have used this exact tonearm, and think the later TH-hold design tonearm used on the JL-F50, which I’ve also used (on a different model JVC turntable owned by my brother) is a superior design.
I expect that if they'd been sold at the same time, the JL-F50 would have been about 50% more expensive than the VL-5, and probably at roughly 85% of the price of the well-regarded Technics SL-1200 MkII, a slightly newer (by about 2 years) design. That would make it very much a '4 digit' turntable in today's money!

The VL-5 would probably be a mid-3-digit turntable - I'd estimate maybe $600-$700.