You’ll want something that can do a wide range of sites, from the smalls (DDs) to larges(max of BB). Navy destroyers are fairly cheap and are able to take on all the sites (larges may need focused skills or multiple pilots to have enough dps to break the rat). A lot of the PVP is really just picking your fights, if you see a caracal or Navy Osprey on dscan for example, you will want to align and warp away when they come into your site rather than sticking around. If you do go with the larger ships, just realize that you are limited in the sites you can enter, and even more so if you go with T2/pirate.
My personal favorite ship the Caldari Navy Hookbill. Very versatile with loads of different fits. My favorite cheap variant is probably the Dual Rep Hookbill, with a Medium Anci Shield Rep - Small Anci Armor Rep combo. My favorite expensive variant is the True Faction polarized CNH, with either two medium shield extenders and no scram or one MSE and the scram, in addition to 2 webs and an AB. Ran with either Snakes for dishonor or Nirvana implants. I have gotten 500dps out of stupid PYFA numbers.