I run as small as a bar as I can and still easily buck what I am cutting. Unless I want the reach for limbing or brushy crap. My 60cc saw wears a 20" and Fair bit. However I have smaller saws for smaller wood. If it is your only saw I would consider an 18 and 24 .
As far as bar choices well if I was looking on a budget I would look real hard at GB Bars. I have also had good luck with forester bars. If I wanted a better bar i would look at Total bars. Member
@fordf150 sells them and even has an adapter so you can run stihl mount bars giving you a lot more options. Oregon bars are probably the most common I have had good results with the power match but the cost about the same price as a total.
Hope this info helps.