Trip quality is pretty awful on all the narrowbody fleets right now. 73 and 320 have a lot more variety but the 717 has no redeyes and faster seniority progression. It's really just a matter of deciding what is more important to you - holding weekends/holidays off but having RJ-type flying on the 717 or doing more interesting flying and making a bit more money but staying junior longer on the 73 or bus.