There is practically no advantage to living on Venus other than that you get gravity. The only local resources available are the atmosphere, and you need to create a floating habitat that is also an interplanetary spacecraft port. Frankly, that's actually pretty far outside our realm of technology at present.

Mars has many more advantages in comparison. For one you can build on the surface of the planet. There are many resources on Mars that can be exploited almost immediately and many others that can be exploited over a longer term: the atmosphere can be used to help produce rocket propellant, water can be used to aid in that as well. Things like iron/steel, glass, plastics, concrete, etc. can all be produced on Mars with a minimal industrial base within the first decade of colonization, with increasing quality and throughput over time. These things are important because they significantly advantage Martian colonies in terms of their ability to be partially self-sufficient and partially self-reliant in regards to expansion.

On Venus practically every ounce of material in the colony needs to be shipped from Earth, it's scarcely better than an orbital station. On Mars you can rely on local supplies for water, for propellant for the return trip, for fuel and oxidizer for ground machinery (mining vehicles) and emergency backup power. You can grow crops using Martian sunlight, Martian CO2, Martian water, Martian Nitrogen, and Martian soil. You can use solar energy for power and sunlight to grow crops as on Earth, the lower light levels are slightly misleading, Mars doesn't have routine cloud cover and has a thinner atmosphere so the average amount of watt-hours per area per day on Mars are very similar to what they are on Earth. You can use regolith for radiation shielding and in construction (building roads, for example). You can manufacture concrete, steel, glass, and plastics using local materials so that you can begin building things like habitats, industrial facilities, etc. using substantially locally produced materials while relying on Earth-produced components for only a subset of the mass of the things that get built, and an ever decreasing subset at that.

A Mars colony would be one that should grow in size and capabilities by leaps and bounds year over year as local industry and agriculture ramps up, as exploitation of local resources increases and improves, as techniques for making use of those local resources scale up and become increasingly sophisticated.

Venus just doesn't rate in comparison. Nobody has a design for how you'd build a floating habitat on Venus that would be reliable enough to trust for decades. One that could also serve as a spaceport for spaceships.

We have the technology to tackle Mars colonization now, it only requires following through on doing it. And Mars has the resources to make colonization a feasible concern that increases its ability to support a population, increases its level of technological sophistication, increases its industrial and agricultural base substantially every year, year after year, indefinitely. That's why Mars is such an attractive target. You can plant a civilization there in a way that you can't, with our level of technology, on the Moon or Venus.