Easiest job to gear and get put into endgame content right away is probably WHM. (Playing optimally is a different story) WHMs are always in need
GEO is probably second easiest job to gear and easiest job to play (but people normally only look for Idris geo even though 900 skill is fine for most if not all content). This job is normally used throughout all content
COR is probably the the most fun job to play IMO but it's one of the most expensive jobs to gear. Minimal gearsets required to play this job and actually be contributing will cost you a pretty penny. Some people might not want to take you if you don't even have a rare/ex neck piece from the hardest boss in Omen (Ou's Regal Necklace) which is difficult for a returning player to acquire (without mercing). Though this is a bahamut thread and not an Asura one so maybe there's a difference in that. This job is normally used throughout all content
BRD requires a huge gil & time investment as well. Most people won't take you unless you're 4 song Honor march brd to real content. Which requires Aeonic horn, Empy Harp, and relic horn to cap out your songs. (Again this is my experience on Asura, maybe it's different on bahamut) This job is normally used throughout all content