Sensors are certainly a factor that need to be considered when looking at ships, but they are not the only factor.
The Tartan and the CR-90A are both rather slow ships, with only a hyper of 2. The Namana has a 3, and the Bayonet has a 4. While the Tartan wins on sensors with 12, the speed advantage of the Bayonet (and to a lesser degree the Namana) cannot be understated, as travel times are already long enough in this game. You certainly don't want to be going beyond your immediate area with a hyper 2 ship. The Bayonet and Namana also have a wider range of weapons than the Tartan, and could be argued to be better armed (although it depends how Turbolasers stack up to Heavy Lasers). The Tartan does have the advantage in hull and shields. The CR-90A is certainly the least well armed and armoured of the four.
The C-3, mentioned earlier, is the fastest capship available with hyper 6, does come with 8 sensors, but is weakly armoured and completely unarmed. It also lacks the landing capacity of the other 4, so an accompanying "shuttle" ship is a must. If you're transporting NPCs, the capacity of your other ship then also becomes a factor.
If you're looking for something with more bite, there's always the Kaloth. There usually seems to be plenty of them on CPM, and while they're slow (hyper 2), they have 8 sensors, and are probably the best armed ship that's generally available, combined with survivability on par with the Tartan. The other downside besides the speed is that, like the C-3, they do not land, making an additional "shuttle" vessel a requirement.
____________"May the Grace of Ara go with you, and His Vengeance be wrought upon your enemies."
Only fools and children dream of heroes.