Depends on which 7 you're talking about.
Are we talkin e65? Pre-facelift e65's are fuuhh-huuuhh-HUGLY. Post-facelift one's are perfectly fine looking, have an improved iDrive, a stronger engine, and improved electronic reliability. Granted, you could easily get a pre-FL e65 for under $35k-40k, which makes them a bargain, but still, they're definitely not as good as the newer ones.
If you're talking about an e38 7er ('94-'01), then just make sure it's in good condition. They're about the same size interior-wise as a current gen 5er.
I'd take the M3 any day to be honest, but that's just because of my age I guess.
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Past: '08 E92 335i|ZPP|ZSP|6AT
Past: '15 Mustang GT|401A|PP|6MT
Current: '20 Shelby GT350|6MT
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