I have tried Sidewinder, Eagle, Viper and Cobra.
All three first were amazing...specially the eagle(but has a lot of limitations)
But the Cobra didn't felt like a specialized fighter...So i went Viper...Im upgrading getting more A items, I can take Anacondas without issues...But always carry your chaff and at least one Shield Cell
yep it's a decent ship once you spent 3 millions 500k, good speed, normal maneuverability, the drawbacks are extreme tho: Power starving, 13 Ly jump range, very few and small internals, not the fastest ship, extreme weight punishment, and only 1 profession available Bounty hunter
rather than suffer from it's extreme weaknesses and have to spent a lot of money into it, you could also spent 2 millions on a Cobra, and do everything better than the viper with a lot of other possibilities, like 20 Ly jump, every upgrade without any problem in power or weight, extreme internals, more tanky, use the weapons you want, with better Warrant scanner, extreme fuel tank, every profession available at the same time...
all in all, the
Cobra: is the best fighter, the fastest ship and can do everything else at the same time
the viper: is only good for fight, second best in speed, and can only do bounty hunter (can't even use more than a class C Warrant scanner tho), with incredible weaknesses and needs the perfect sacrifice build with maxed upgrades to make it decent.