It seems like the Honda CB500 has been a staple commuter bike since the dawn of time when wheels were invented and some prophet stuck one in front of the other to courier stone tablets about. The CB500 is slightly older (pre-2004), but both share a nigh identical parallel-twin 499cc engine. Early CB500s (pre-1997) had a rear drum brake and later CBF500s had the option of ABS. The 2004 Honda CBF500 also swapped in an adjustable rear mono-shock to improve handling.
The Honda CB500S variant had a bikini fairing, but the rest were all naked. For years the CB/CBF500 was the default and ubiquitous choice for couriers and training schools. They are insanely reliable and often keep on going into six-digit mileage. Expect a solid and capable commuter, just not the most exciting. Prices can start very low for older tatty examples and later ABS-equipped models do demand a premium, but a decent one can be had for below £2000. Insurance is dirt cheap too. All of this puts the CBF500 top of any first big bike recommendations.
As with any old, well-used bike, check if the downpipes are rotten or forks pitted and if there is any particularly bad damage from inevitable mishaps. Also check the lower shock mounting on the swing arm of the Honda CBF500, as this is exposed to crud from the wheel and can seize up solid. Unfortunately, a centre stand wasn’t standard.